MR. JUSTICE MARSHALL delivered the opinion of the Court.This case presents the question whether provisions of the collective bargaining agreement between the International Longshoremen's Association (ILA) and employer organizations in the shipping industry which were adopted in response to the technological innovation of containerized shipping are a lawful work preservation agreement.  The National Labor Relations Board held that the provisions did not preserve traditional work opportunities for employees represented by the union, but sought instead to acquire work they had not previously performed; therefore, it concluded that the provisions violated § 8(e) of the National Labor Relations Act, 29 U.S.C. § 158(e), and union action to enforce them violated § 8(b)(4)(b) of the Act, 29 U.S.C. § 158(b)(4)(b).  International longshoremen's Assn. (Dolphin Forwarding, Inc.), 236 N.L.R.B. 525 (1978); International Longshoremen's Assn. (Associated Transport, Inc.), 231 N.L.R.B. 351 (1977).  A divided panel of the United States Court of Appeals for the District of Columbia Circuit declined to enforce the Board's orders.  198 U.S.App.D.C. 157, 613 F.2d 890 (1979).  We granted certiorari, 444 U. S. 104 (1980), to resolve a conflict among the Circuits on this important question of federal labor law. [Footnote 1]IThis controversy arises out of the collective bargaining response of the ILA and the east coast shipping industry to Page 447 U. S. 494 containerization, a technological innovation which has had such a profound effect on that industry that it has frequently been termed "the container revolution." [Footnote 2]  In the words of one observer, "containerization may be said to constitute the single most important innovation in ocean transport since the steamship displaced the schooner." [Footnote 3]AContainers are large, reusable metal receptacles, ranging in length from 20 to 40 feet and capable of carrying upwards of 30,000 pounds of freight, which can be moved on and off an ocean vessel unopened.  Container ships are specially designed and constructed to carry the containers, which are affixed to the hold.  A container can also be attached to a truck chassis and transported intact to and from the pier like a conventional trailer.The use of containers is substantially more economical than traditional methods of handling ocean-borne cargo. [Footnote 4]  Because cargo does not have to be handled and repacked as it moves from the warehouse by truck to the dock, into the vessel, then from the vessel to the dock and by truck or rail to its destination, the costs of handling are significantly reduced.  Expenses of separate export packaging, storage, losses from pilferage and breakage, and costs of insurance and processing cargo documents may also be decreased.  Perhaps most significantly, Page 447 U. S. 495 a container ship can be loaded or unloaded in a fraction of the time required for a conventional ship. [Footnote 5]  As a result, the unprofitable in-port time of each ship is reduced, and a smaller number of ships are needed to carry a given volume of cargo. [Footnote 6]Before the introduction of container ships, and as is still the case with conventional vessels, trucks delivered loose, or break-bulk, cargo to the head of the pier.  The cargo was then transferred piece by piece from the truck's tailgate to the ship by longshoremen employed by steamship or stevedoring companies.  The longshoremen checked the cargo, sorted it, placed it on pallets and moved it by forklift to the side of the ship, and lifted it by means of a sling or hook into the ship's hold. [Footnote 7]  The process was reversed for cargo taken off incoming ships.  With the advent of containers, the amount of on-pier work involved in cargo handling has been drastically reduced, since the cargo need not be loaded and unloaded piece by piece.  The amount of work available for longshoremen has been further reduced by the shipping companies' practice of making their containers available to shippers Page 447 U. S. 496 and consolidators [Footnote 8] for loading and unloading away from the pier.Containerization, then, was a technological advance of great importance to the shipping industry which, at the same time, threatened the jobs of longshoremen by dramatically increasing their productivity. [Footnote 9]  As one might expect, the subject has been a hotly disputed topic of collective bargaining between the union and the employers. [Footnote 10]  We are concerned with the results of that collective bargaining process as it affects the shipping industry in the Ports of New York, Baltimore, and Hampton Roads, Va.BIt is necessary, in discussing the collective bargaining agreements here at issue, to define certain industry terms of art Page 447 U. S. 497 pertaining to containerized cargo.  Loading cargo into a container is called "stuffing"; unloading cargo from a container is called "stripping."  Containers holding goods beneficially owned by one shipper or consignee are called full shippers' loads (FSL).  Containers holding goods belonging to more than one shipper or consignee are called consolidated container loads.  Such cargo is also called "less than trailer load" (LTL) or "less than container load" (LCL) cargo.The first collective bargaining agreement to contain a provision dealing with containerized shipping was the 1959 agreement between ILA and the New York Shipping Association (NYSA).  At that time, containerization was in its infancy. [Footnote 11]  The provision in the 1959 agreement was prompted by a dispute over the use of Dravo containers, boxes eight cubic feet in size.  See International Longshoremen's Assn. (Consolidated Express, Inc.), 221 N.L.R.B. 956, 957 (1975), enf'd, 537 F.2d 706 (CA2 1976), cert. denied, 429 U.S. 1041 (1977).  The agreement recognized the right of NYSA members "to use any and all type [sic] of containers without restriction or stripping by the union."  221 N.L.R.B. at 957.  In return, NYSA agreed to contribute royalty payments on "containers which are loaded or unloaded away from the pier by non-ILA labor."  Ibid.  The agreement also provided:"Any work performed in connection with the loading and discharging of containers for employer members of NYSA which is performed in the Port of Greater New York whether on piers or terminals controlled by them, Page 447 U. S. 498 or whether, through direct contracting out, shall be performed by ILA labor at longshore rates."Ibid.After the 1959 agreement was reached, the development of container shipping accelerated.  In 1967, ILA demanded in collective bargaining negotiations that longshoremen stuff and strip all containers crossing the piers.  Following a lengthy strike, ILA and NYSA in 1969 adopted, as part of their 1968-1971 collective bargaining agreement, the Rules on Containers (Rules).  The terms of that master agreement were adopted by other ports on the North Atlantic coast, including Hampton Roads and Baltimore.  The Rules were slightly modified in 1971, after another long strike.  In 1973, ILA and the Council of North Atlantic Shipping Associations (CONASA) executed the "Dublin Supplement" as an "interpretive bulletin" to the Rules.  The substance of the Dublin Supplement was incorporated in the version of the Rules contained in the 1974-1977 collective bargaining agreement. [Footnote 12]In essence, the Rules contained in the 1968 and 1971 agreements provided that, if containers owned or leased by the shipping companies and carrying LTL or consolidated container loads were to be stuffed or stripped within the local port area (that is, within a geographical radius of 50 miles of the port) by anyone other than the employees of the beneficial owner of the cargo, that work must be done at the piers by ILA labor.  The shipping companies were required to pay a royalty on containers that passed over the piers intact, as well as liquidated damages, presently set at $1,000 per container, for any container handled in violation of the Rules.  The Dublin Supplement declared that the Rules applied to all containers, including those designated as FSL containers, which were stuffed or stripped in the local area by other than the beneficial owner's own employees.  The Supplement also noted an exception for FSL containers warehoused locally for at least 30 days, and, as a method of enforcing the Rules, Page 447 U. S. 499 prohibited the employers from releasing any of their containers to known consolidators with facilities located within 50 miles of the port.Thus, under the final version of the Rules incorporated in the 1974 agreement, if containers owned or leased [Footnote 13] by the shipping companies are to be stuffed or stripped locally by anyone other than the employees of the beneficial owner of the cargo, that work must be done at the piers by ILA labor.  FSL containers that are transported intact to or from the beneficial owner or that are warehoused locally for 30 days, and consolidated containers coming from or bound for points outside the local area, do not have to be stuffed and stripped by ILA members.  The practical effect of the Rules is that some 80% of containers pass over the piers intact.  App. 612.  The remaining 20% are stuffed and stripped by longshoremen, regardless of whether that work duplicates work done by non-ILA employees off-pier.CThis case involves two proceedings before the National Labor Relations Board (Board) on charges that the Rules are illegal secondary activity in violation of federal labor law.  The cases were consolidated on appeal.  The Dolphin proceeding, 236 N.L.R.B. 525 (1978), concerns the application Page 447 U. S. 500 of the provisions on LCL cargo to containers used by consolidators operating within 50 miles of the Port of New York.  The Associated Transport proceeding, 231 N.L.R.B. 351 (1977), concerns the application of the Rules to FSL containers whose cargo was transferred by truckers to their own trucks within 50 miles of the Ports of Baltimore and Hampton Roads.  The affected truckers and consolidators filed unfair labor practice charges with the Board, alleging that the Rules constituted a "hot cargo" agreement in violation of § 8(e) of the National Labor Relations Act (Act), and that the activities of the parties to the agreement in enforcing its terms were an illegal secondary boycott prohibited by § 8(b)(4)(b) of the Act.The facts underlying the charges may be briefly stated.  Dolphin Forwarding, Inc. (Dolphin), and San Juan Freight Forwarding, Inc. (San Juan), were NVOCC consolidators, see n 8, supra, soliciting business from shippers throughout the United States who wished to transport LCL cargo between New York and Puerto Rico. [Footnote 14]  Dolphin and San Juan received their customers' goods at their off-pier facilities, located within 50 miles of the Port of New York.  Using subcontracted non-ILA labor, they consolidated the goods of two or more shippers, stuffed them into containers provided by members of NYSA, and had the filled containers trucked to the pier to be loaded onto ships by longshoremen. [Footnote 15]  As a result of these practices, the NYSA members who had supplied their containers to the consolidators were assessed liquidated damages of approximately $47,000.  Those carriers then Page 447 U. S. 501 informed Dolphin and San Juan that they would no longer furnish them with containers.  Thereupon, Dolphin and San Juan filed unfair labor practice charges with the Board.Houff Transport, Inc. (Houff), and Associated Transport, Inc. (Associated), [Footnote 16] were Interstate Commerce Commission-licensed common carriers who operated motor freight terminals within 50 miles of the Ports of Baltimore and Hampton Roads.  Since the advent of containerization, they had transported FSL container loads to consignees both within and beyond the 50-mile radius, and routinely stripped such FSL containers and restuffed the cargo into their own vehicles for reasons of economy, safety, or state highway or bridge regulations.The practice of using non-ILA labor to strip and restuff FSL cargo within the 50-mile radius is known as shortstopping.  Although the Rules, prior to the Dublin Supplement, did not expressly discuss FSL cargo, see App. 235-250, 270276, the ILA and the shipping companies apparently regarded shortstopping as an infraction, see 198 U.S.App.D.C. at 162, 613 F.2d  at 895; 231 N.L.R.B. at 355 (Fanning, Chairman, dissenting).  The Dublin Supplement, and subsequent versions of the Rules, provided that ILA labor must handle all FSL containers that otherwise would be handled within the local area by other than the consignee's own employees, except for FSL cargo consigned to the beneficial owner's place of business or warehoused for 30 days within the port area.After the new Rules became effective, Houff and Associated shortstopped containers picked up from CONASA members.  The shipping companies were assessed liquidated damages for each such container.  When Houff and Associated refused to indemnify them for the fines, the shipping companies canceled their interchange agreements.  Houff, Associated, and the Tidewater Motor Truck Association (TMTA), an association Page 447 U. S. 502 of which Associated was a member, filed unfair labor practice charges.In holding that the charges were substantiated in both the Dolphin and Associated Transport proceedings, the Board relied on its previous decision in International Longshoremen's Assn. (Consolidated Express, Inc.), 221 N.L.R.B. 956 (1975), enf'd, 537 F.2d 706 (CA2 1976), cert. denied, 429 U.S. 1041 (1977) (hereinafter Conex). [Footnote 17]  In Conex, the Board held that the traditional work of longshoremen has been to load and unload ships at the pier.  As the Board explained in the Dolphin proceeding, Conex"held that the Rules were not valid work-preservation clauses in that, traditionally, the off-pier stuffing and stripping of containers was performed by consolidating companies, and not longshoremen.  Since the work was not traditional longshore work and had never been performed by longshoremen, the Rules which required the shipping companies to stop doing business with consolidators did not have a lawful work-preservation object."236 N.L.R.B. at 526.  Similarly, in the Associated Transport proceeding, the Board affirmed the finding by the Administrative Law Judge (ALJ) of an unfair labor practice because longshoremen "had not historically done the work" of stripping FSL containers away from the pier.  231 N.L.R.B. at 353 (emphasis in original).  Page 447 U. S. 503 In short, in the Board's view the Rules sought to acquire for ILA members work that had historically been performed not by longshoremen, but by employees of consolidators and truckers.  Therefore the Rules had a secondary objective forbidden by the Act.ILA and CONASA appealed to the Court of Appeals, and the Board cross-applied for enforcement of its orders. [Footnote 18]  The cases were consolidated.  A divided panel of the Court of Appeals refused enforcement, holding that the Board had erred as a matter of law in defining the work in controversy.  It therefore vacated the Board's decisions, denied its applications for enforcement, and remanded the cases for further proceedings.  We affirm.IISection 8(b)(4)(B) of the Act [Footnote 19] prohibits unions and their agents from engaging in secondary activities whose object is to force one employer to cease doing business with another.  Section 8(e) [Footnote 20] makes unlawful those collective Page 447 U. S. 504 bargaining agreements in which the employer agrees to cease doing business with any other person.  Although § 8(e) does not, in terms, distinguish between primary and secondary activity, we have held that, as in § 8(b)(4)(B), Congress intended to reach only agreements with secondary objectives.  See NLRB v. Pipefitters, 429 U. S. 507,  429 U. S. 517 (1977) (hereinafter Pipefitters); National Woodwork Manufacturers Assn. v. NLRB, 386 U. S. 612,  386 U. S. 620, 635 (1967) (hereinafter National Woodwork) .Among the primary purposes protected by the Act is "the purpose of preserving for the contracting employees themselves work traditionally done by them."  Pipefitters, supra at  429 U. S. 517.  Whether an agreement is a lawful work preservation agreement depends on"whether, under all the surrounding circumstances, the Union's objective was preservation of work for [bargaining unit] employees, or whether the [agreement was] tactically calculated to satisfy union objectives elsewhere. . . .  The touchstone is whether the agreement or its maintenance is addressed to the labor relations of the contracting employer vis-a-vis his own employees."National Woodwork, supra at  386 U. S. 644-645 (footnotes omitted).  Under this approach, a lawful work preservation agreement must pass two tests:  first, it must have as its objective the preservation of work traditionally performed by employees represented by the union.  Second, the contracting employer must have the power to give the employees the work in question -- the so-called "right of control" test of Pipefitters, supra.  The rationale of the second test is that, if the contracting employer has no power to assign the work, it is reasonable to infer that the agreement has a secondary objective, Page 447 U. S. 505 that is, to influence whoever does have such power over the work."Were the latter the case, [the contracting employer] would be a neutral bystander, and the agreement or boycott would, within the intent of Congress, become secondary."National Woodwork, supra at  386 U. S. 644-645.In applying the work preservation doctrine, the first and most basic question is:  what is the "work" that the agreement allegedly seeks to preserve?  Sometimes the process of identifying the work at issue will require no subtle analysis.  In National Woodwork, for example, the agreement preserved for the carpenters employed by a general contractor the work of fitting all doors installed on the jobsite.  This was work they had always done, and the method the parties chose to preserve the carpenters' right to that work was simply to prohibit the employer from purchasing any doors that had been prefitted by any other employees.  That the provision incidentally required the employer to boycott all prefitted doors was of no consequence to the validity of the agreement.  See Pipefitters, supra at  429 U. S. 510,  429 U. S. 526.But in many cases, it is not so easy to find the starting point of the analysis.  Work preservation agreements typically come into being when employees' traditional work is displaced, or threatened with displacement, by technological innovation.  The national labor policy expresses a preference for addressing "the threats to workers posed by increased technology and automation" by means of "labor-management agreements to ease these effects through collective bargaining on this most vital problem created by advanced technology."  National Woodwork, supra at  386 U. S. 641,  386 U. S. 642.  In many instances, technological innovation may change the method of doing the work, instead of merely shifting the same work to a different location.  One way to preserve the work of the employees represented by the union in the face of such a change is simply to insist that the innovation not be adopted, and that the work continue to be done in the traditional way.  Page 447 U. S. 506 The union in National Woodwork followed this tactic, and negotiated an agreement in which the employer agreed not to use prefabricated materials.  We held that agreement was lawful under §§ 8(e) and 8(b)(4)(B).  But the protection Congress afforded to work preservation agreements cannot be limited solely to employees who respond to change with intransigence.  Congress, in enacting § 8(e), did not intend to protect only certain kinds of work preservation agreements; rather, it "had no thought of prohibiting agreements directed to work preservation," National Woodwork, supra at  386 U. S. 640.  The work preservation doctrine, then, must also apply to situations where unions attempt to accommodate change while preserving as much of their traditional work patterns as possible. [Footnote 21]  When this is the case, the inquiry must be more refined, and the analysis more discriminating.  The Board held that"'[t]he traditional work of the longshoremen represented by ILA has been to load and unload ships.  When necessary to perform their loading and unloading work, longshoremen have been required to stuff and strip containers on the piers.'"231 N.L.R.B. at 364 (decision of ALJ, adopted by the Board), quoting Conex, 221 N.L.R.B. at 959; see 236 N.L.R.B. at 526.  The Board then determined that the work in controversy was "the off-pier stuffing and stripping of containers," ibid.; see 231 N.L.R.B. at 364-365.  Similarly, in Conex, the Board stated:"It is clear from the record that the work in controversy here is the LCL and LTL container work performed by [the charging parties] at their own off-pier premises."221 N.L.R.B. at 959.  Because ILA members had never performed such work, the Board concluded that the Rules were an illegal attempt to reach out and acquire work that was not within the union's traditional work jurisdiction and which its members had never performed.  We agree with the Court of Appeals that this Page 447 U. S. 507 approach to defining the work at issue was incorrect as a matter of law.The Board's approach reflects a fundamental misconception of the work preservation doctrine as it has been applied in our previous cases.  Identification of the work at issue in a complex case of technological displacement requires a careful analysis of the traditional work patterns that the parties are allegedly seeking to preserve, and of how the agreement seeks to accomplish that result under the changed circumstances created by the technological advance.  The analysis must take into account "all the surrounding circumstances," National Woodwork, 386 U.S. at  386 U. S. 644, including the nature of the work both before and after the innovation.  In a relatively simple case, such as National Woodwork or Pipefitters, the inquiry may be of rather limited scope.  Other, more complex cases will require a broader view, taking into account the transformation of several interrelated industries or types of work; this is such a case.  Whatever its scope, however, the inquiry must be carefully focused:  to determine whether an agreement seeks no more than to preserve the work of bargaining unit members, the Board must focus on the work of the bargaining unit employees, not on the work of other employees who may be doing the same or similar work, [Footnote 22] and examine the relationship between the work as it existed before the innovation and as the agreement proposes to preserve it.The Board, by contrast, focused on the work done by the employees of the charging parties, the truckers and consolidators, after the introduction of containerized shipping.  It found that work was similar to work those employees had done before the innovation, and concluded that ILA was Page 447 U. S. 508 trying to acquire the traditional work of those employees.  That conclusion ignores the fact that the impact of containerization occurred at the interface between ocean and motor transport; not surprisingly, the work of stuffing and stripping containers is similar to work previously done by both longshoremen and truckers.  The Board's approach would have been entirely appropriate in considering an agreement to preserve the work of truckers' employees, but it misses the point when applied to judge this contract between the ILA and the shipowner employers.By focusing on the work as performed, after the innovation took place, by the employees who allegedly have displaced the longshoremen's work, the Board foreclosed -- by definition -- any possibility that the longshoremen could negotiate an agreement to permit them to continue to play any part in the loading or unloading of containerized cargo.  For the very reason, the Rules were negotiated was that longshoremen do not perform that work away from the pier, and never have.  Thus, it is apparent that, under the Board's approach, in the words of the Court of Appeals, the "work preservation doctrine is sapped of all life."  198 U.S.App.D.C. at 176, 613 F.2d  at 909.That this is so is vividly demonstrated by considering how different would have been the results in National Woodwork and Pipefitters if we had adopted the approach now chosen by the Board.  In National Woodwork, we held that carpenters could seek to preserve their traditional work of finishing blank doors at the construction jobsite by prohibiting the employer, a general contractor, from purchasing prefinished doors from the factory.  If we had followed the Board's current approach in analyzing the agreement, we would have defined the work in controversy as "the finishing of blank doors away from the construction site."  That work, of course, had never been done by the carpenters employed by the general contractor, but had been performed by the employees of Page 447 U. S. 509 the door manufacturers since before the adoption of the agreement.  We would perforce have determined that the object of the agreement was work acquisition, not work preservation.Similarly, Pipefitters involved an agreement between a subcontractor and a pipefitters' union that pipe threading and cutting were to be performed on the jobsite.  Relying on the agreement, the union refused to install climate-control units whose internal piping had been cut, threaded, and installed at the factory.  The Board held that the provision was a lawful work preservation agreement, but that the refusal to handle the pre-piped units was an unfair labor practice because the units had been specified by the general contractor and the subcontractor had no power to assign the employees the work they sought.  Neither the Court of Appeals nor this Court questioned the validity of the work preservation clause but for the fact that it was enforced against an employer who could not control the work.  Under the Board's current approach, however, the "work" would have been "cutting, threading, and installing pipe in climate-control units at the factory."  Since the bargaining unit employees had never performed that work, there would have been no reason to reach the "right of control" issue.Thus, the Board's determination that the work of longshoremen has historically been the loading and unloading of ships should be only the beginning of the analysis.  The next step is to look at how the contracting parties sought to preserve that work, to the extent possible, in the face of a massive technological change that largely eliminated the need for cargo handling at intermediate stages of the intermodal transportation of goods, and to evaluate the relationship between traditional longshore work and the work which the Rules attempt to assign to ILA members. [Footnote 23]  This case presents Page 447 U. S. 510 a much more difficult problem than either National Woodwork or Pipefitters, because the union did not simply insist on doing the work as it had always been done and try to prevent the employers from using container ships at all -- though such an approach would have been consistent with National Woodwork and Pipefitters.  Instead, ILA permitted the great majority of containers to pass over the piers intact, reserving the right to stuff and strip only those containers that would otherwise have been stuffed or stripped locally by anyone except the beneficial owner's employees.  The legality of the agreement turns, as an initial matter, on whether the historical and functional relationship between this retained work and traditional longshore work can support the conclusion that the objective of the agreement was work preservation. rather than the satisfaction of union goals elsewhere. [Footnote 24]  Respondents assert that the stuffing and stripping reserved for the ILA by the Rules is functionally equivalent to their former work of handling break-bulk cargo at the pier. [Footnote 25]  Petitioners-intervenors, on the other hand, argue that containerization has worked such fundamental changes in the industry that the work formerly done at the pier by both longshoremen Page 447 U. S. 511 and employees of motor carriers has been completely eliminated.These questions are not appropriate for initial consideration by reviewing courts.  They are properly raised before the Board, whose determinations are, of course, entitled to deference.  Since the Board has not had an opportunity to consider these questions in relation to a proper understanding of the work at issue, we will not address them here.  We emphasize that neither our decision nor that of the Court of Appeals implies that the result of the Board's reconsideration of this case is foreordained. [Footnote 26]  Viewing the work allegedly to be preserved by the Rules from the proper perspective, the Board will be free to determine whether the Rules represent a lawful attempt to preserve traditional longshore work, or whether, instead, they are "tactically calculated to satisfy union objectives elsewhere," National Woodwork, 386 U.S. at  386 U. S. 644.  This determination will, of course, be informed by an awareness of the congressional preference for collective bargaining as the method for resolving disputes over dislocations caused by the introduction of technological innovations in the workplace, see id. at  386 U. S. 641-642.  Thus, in judging the legality of a thoroughly bargained and apparently reasonable accommodation to technological change, the question is not whether the Rules represent the most rational or efficient response to innovation, but whether they are a legally permissible effort to preserve jobs.If the Board finds, on remand, that the Rules have a lawful work preservation objective, it will then, of course, be obliged Page 447 U. S. 512 to consider the charging parties' contention that CONASA members did not have the right to control the stuffing and stripping of containers.  Because the Board held that the agreement was directed at work acquisition, rather than work preservation, it did not decide the right-to-control issue in this case.  That issue remains open on remand.  Therefore, and because the arguments of the parties were necessarily addressed to an erroneous conception of the work whose control was disputed, [Footnote 27] any discussion of that issue here would be premature.  Respondents have also argued that the employers, as common carriers who are subject to Government regulation and to the provisions of their own tariffs, shippers' bills of lading, and intermodal interchange agreements with motor carriers, have no legal right to withhold containers or container services from their customers on a selective basis, to condition access to the containers on compliance with the Rules, to seek indemnification from their customers for fines imposed under the Rules, or to enforce the Rules after the containers have been released to motor carriers.  See, e.g., Shipping Act, 1916, 46 U.S.C. § 801 et seq.; Intercoastal Shipping Act, 1933, 46 U.S.C. § 843 et seq.; Sea-Land Service, Inc. -- Proposed ILA Rules on Containers, 20 F.M.C. 788 (1978), review pending, No. 78-1776 (CADC).  These contentions present difficult and complex problems which are not properly before us.We conclude that the Court of Appeals correctly held that the Board's definition of the work in controversy in this dispute was erroneous as a matter of law, and we therefore affirm the Court of Appeals' judgment vacating the Board's decisions, Page 447 U. S. 513 denying the applications for enforcement, and remanding to the Board for further proceedingsIt is so ordered
U.S. Supreme CourtNLRB v. Int'l Longshoremen's Assn., 447 U.S. 490 (1980)National Labor Relations Board v. InternationalLongshoremen's Association, AFL-CIONo. 79-1082Argued April 22, 1980Decided June 20, 1980447 U.S. 490SyllabusThis case presents the question whether Rules on Containers (Rules) in a collective bargaining agreement between the International Longshoremen's Association (ILA) and employer organizations in the shipping industry which were adopted in response to the technological innovation of containerized shipping are a lawful work preservation agreement.  The new technology involves the use on specially designed ships of large, reusable metal receptacles which can be moved on and off the vessel unopened and which can be attached to a truck chassis and transported intact to and from the pier, saving costs and time in loading and unloading ships and in warehousing cargo, as compared with the amount of on-pier work involved in handling loose cargo for conventional ships.  The amount of work available for longshoremen has been further reduced by the shipping companies' practice of making their containers available for loading (stuffing) and unloading (stripping) away from the pier by shippers and by freight consolidators who combine the goods of various shippers into a single shipment.  The Rules permit the great majority of containers to pass over the piers intact, reserving to the ILA the right to stuff and strip at the pier only those containers that would otherwise be stuffed or stripped "locally" (within a 50-mile radius of the port) by anyone except employees of the beneficial owner of the cargo, the shipping company being liable for specified liquidated damages for any container handled in violation of the Rules.  Separate unfair labor practice proceedings were brought before the National Labor Relations Board (Board) by truckers and consolidators who, because of the operation against shipping companies of the Rules' liquidated damages provisions, could no longer perform local stuffing and stripping services.  The Board concluded that the Rules were not valid work preservation clauses because the work of stuffing and stripping containers away from the pier had not traditionally been done by ILA members, but had instead been performed by employees of consolidators and truckers.  It therefore held that the Rules violated § 8(e) of the National Labor Relations Act, which makes unlawful those collective bargaining agreements whereby the employer agrees to cease doing business with any other person, and that union action to enforce Page 447 U. S. 491 the Rules violated § 8(b)(4)(b), which prohibits unions from engaging in secondary activities whose object is to force one employer to cease doing business with another.  The Court of Appeals, consolidating the cases and holding that the Board had erred as a matter of law in defining the work in controversy, vacated the Board's decisions, denied its applications for enforcement, and remanded the cases.Held:  The Board's definition of the work in controversy in this dispute was erroneous as a matter of law.  Pp.  447 U. S. 503-513.(a) To constitute a lawful work preservation agreement, the agreement must have as its objective the preservation of work traditionally performed by employees represented by the union, and the contracting employer must have the power to give the employees the work in question.  The first and most basic question is:  what is the "work" that the agreement allegedly seeks to preserve?  Cf. NLRB v. Pipefitters, 429 U. S. 507; National Woodwork Manufacturers Assn. v. NLRB, 386 U. S. 612.  Pp.  447 U. S. 504-505.(b) Identification of the work at issue in a complex case of technological displacement requires a careful analysis of the traditional work patterns that the parties are allegedly seeking to preserve, and of how the agreement seeks to accomplish that result under the changed circumstances created by the technological advance.  The inquiry must focus on the bargaining unit employees' work, not on the work of other employees who may be doing the same or similar work, and must examine the relationship between the work as it existed before the innovation and as the agreement proposes to preserve it.  P.  447 U. S. 507.(c) The Board's conclusion that the "work in controversy" was the off-pier stuffing and stripping of containers erroneously focused on the work done by the employees of truckers and consolidators after the introduction of containerized shipping.  That approach foreclosed, by definition, any possibility that the longshoremen could negotiate an agreement to permit them to play any part in the loading and unloading of containerized cargo.  The Board's determination that the traditional work of ILA members was to load and unload ships should have been only the beginning of the analysis.  The next step is to look at how the contracting parties sought to preserve that work, to the extent possible, in the face of a massive technological change that largely eliminated the need for cargo handling at intermediate stages of the intermodal transportation of goods, and to evaluate the relationship between traditional longshore work and the work which the Rules attempt to assign to ILA members.  Pp.  447 U. S. 507-510.(d) Viewing the work allegedly to be preserved by the Rules from the proper perspective, the Board on remand will be free to determine Page 447 U. S. 492 whether the Rules represent a lawful attempt to preserve traditional longshore work or whether, instead, they are tactically calculated to satisfy union goals elsewhere.  This determination must be informed by an awareness of the congressional preference for collective bargaining as the method for resolving disputes over dislocations caused by the introduction of technological innovations in the workplace, the question being not whether the Rules represent the most rational or efficient response to innovation, but whether they are a legally permissible effort to preserve jobs.  If the Board finds that the Rules have a lawful work preservation objective, it must then consider the charging parties' contention that members of the employer organization did not have the right to control the stuffing and stripping of containers.  Pp.  447 U. S. 510-512.198 U.S.App.D.C. 157, 613 F.2d 890, affirmed.MARSHALL, J., delivered the opinion of the Court, in which BRENNAN, WHITE, BLACKMUN, and POWELL, JJ., joined.  BURGER, C.J., filed a dissenting opinion, in which STEWART, REHNQUIST, and STEVENS, JJ., joined, post, p.  447 U. S. 522. Page 447 U. S. 493