I don't know who is proposing that laws be ignored.  Both DACA and DAPA provided specific carve-outs and a process to determine of specific people ought to be permitted to remain in the US.  Deferred action is based on the well-established concept of prosecutorial discretion.  Sanctuary cities usually do not collect information re person's immigration status, something that is irrelevant in the prosecution of crime, and/or do not agree to detain persons longer than permitted under local statutes to enable ICE to pick them up.  that is not the same as ignoring the law.  Local law enforcement usually have more than enough to do without being required to enforce federal laws, with which they are usually unfamiliar.