After Ruling Critical of N.S.A., Uncertain Terrain for Appeal WASHINGTON - As Judge Richard J. Leon heard arguments last month in a challenge to a National Security Agency program, he said only one thing was certain. "I'm not sure how I'm going to come out," he said, "but I know it's going upstairs." He meant that appeals were inevitable, first to a federal appeals court in Washington and then to the Supreme Court. On Monday, Judge Leon ruled that the program, which collects records of all Americans" phone calls, is probably unconstitutional. He stayed his order to allow for that anticipated trip upstairs. The appeal will face ideological crosscurrents, Supreme Court opinions pointing in opposite directions and unpredictable judicial voting. But it seems reasonably likely that the case, or a related one, will for the first time result in a definitive legal ruling on the constitutionality of one of the post-Sept. 11 government surveillance programs. Similar cases, including one brought by the American Civil Liberties Union in New York, are pending. Unlike in earlier cases challenging warrantless wiretapping programs, it is likely that judges will no longer decline to hear the new ones based on the objection that the plaintiffs cannot demonstrate that information about them has been collected. Judge Leon was dismissive of the government's halfhearted argument on this point, saying it "defies common sense." The main initial critique of Judge Leon's decision was that it blew past the closest Supreme Court precedent and tried to anticipate where the justices might be heading based on concurring rather than controlling opinions in a 2012 decision. The next stop for the case is the United States Court of Appeals for the District of Columbia Circuit, which, thanks to the recent overhaul of the Senate's filibuster rule, has a majority of Democratic appointees among its active judges. But it may be that nothing turns on that. Writing recently in Judicature magazine, Judge Douglas H. Ginsburg, who was appointed to the District of Columbia Circuit by President Ronald Reagan, noted with satisfaction that a recent empirical study had absolved his court "of the charge, so often leveled in the vacuous but vociferous political debates over the confirmation of a new judge, that the court is a political partisan." His own 2010 opinion in United States v. Maynard, writing for a unanimous three-judge panel with two judges appointed by a Republican president, tends to illustrate his point. The decision, which will be helpful to the challengers to the data collection program, was, curiously, mentioned only in passing by Judge Leon. Judge Ginsburg said the collection of huge troves of data over long stretches of time, producing a mosaic of information, could cross a constitutional line. "A person who knows all of another's travels," Judge Ginsburg wrote, "can deduce whether he is a weekly churchgoer, a heavy drinker, a regular at the gym, an unfaithful husband, an outpatient receiving medical treatment, an associate of particular individuals or political groups - and not just one fact about a person, but all such facts." Alexander A. Abdo, an A.C.L.U. lawyer, echoed that reasoning at the Nov. 22 argument in the New York case, four days after arguments in the case heard by Judge Leon. The telephone records collected by the security agency reveal, Mr. Abdo said, "who you call and when, whether you call your doctor, the domestic violence hotline, an abortion provider, an ex-girlfriend, a suicide hotline or a pastor," he said. And it reveals not just one of those details about every American, but every one of those details. The District of Columbia Circuit's decision, Mr. Abdo said, "could serve as a model for this court." In 1979, in Smith v. Maryland, the Supreme Court said a robbery suspect could not expect that his right to privacy extended to the numbers dialed from his phone. The government says the Fourth Amendment analysis in the new cases should begin and end with that decision. "The government's position is that Fourth Amendment challenge is foreclosed by Smith v. Maryland, which held that there is no reasonable expectation of privacy in the noncontent information that's held by third parties," Stuart F. Delery, a Justice Department lawyer, said at the argument of the A.C.L.U. case. The 2012 decision, United States v. Jones, an appeal from the Maynard decision, unanimously rejected the use of a GPS device to track the movements of a drug suspect over a month. The majority in the 2012 case said that attaching the device violated the defendant's property rights.