When can laws be declared unconstitutional?

Answer 1

When they are subjected to judicial review and determined by the court of jurisdiction to be in conflict with existing rights granted under the US Constitution or the state's constitution where the statute has been challenged.

Answer 2

Yes. In accordance with Marbury v. Madison the United States Supreme Court has the power of judicial review, which grants the court the power to declare a law is not in accordance with the Constitutional and is there for unenforceable, or null and void.

Answer 3

If it is contradictory to a standing Constitutional law. Also, previous court rulings stand as precedents. If cases arise about laws which counter previously set precedents, courts may rule those laws unconstitutional or null and void.

Answer 4

Yes, laws can either be repealed by Act of Congress or repealed pro tanto through a subsequent adverse ruling by the Court. An existing regime can also be outlawed through Constitutional Amendment--as was done with, for example, Prohibition, with Amendment XVIII and its later Constitutional repeal, Amendment XXI (the actual effectuating federal law was colloquially referred to as the Volstead Act).

Although the U.S. Congress can enact laws and also can repeal them, important legislation, such as the Patient Protection and Affordable Care Act ("Obamacare") are often thousands of pages long and take hundreds or thousands of person-hours to produce. It would set a very dangerous precedent for Congress in one legislative session to enact such comprehensive and revisionist legislation, only to repeal it in the next, so that it is off the books as if it had never existed--and by the very next Congress.

Laws enacted by the Congress are subject to execution and enforcement by the executive branch, and it is Constitutionally beyond the purview of the executive branch to refuse to. That said, there is tremendous constitutional latitude in precisely how the executive executes and enforces the law, and it is this latitude that gives rise to political talk of "repeal" or "executive repeal". A true refusal to execute and enforce, however, would give rise to judicial review of executive conduct by the Court, and if, necessary, the issuance of writs of mandamus. In the case of the Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act, National Federation of Independent Business v. Sebelius, 567 U.S. ____ (2012) mostly upheld this legislation, except some of Congress' prerogative to make certain demands of the States as to Medicaid. The likelihood of the Court revisiting a constitutional question as to this anytime soon is so remote as to be beyond mention, except as to its being theoretically possible.

Also, since the enactment of the PPACA and the HCERA, the executive branch has been in pursuit of execution and enforcement of these laws according to their terms, and to the extent of the process of executive rulemaking as to further definition and enactment in and through the Code of Federal Regulations, in addition to the statutory enactments already a part of the United States Code, and its common-law recognition in and by National Federation of Independent Business v. Sebelius.

Any true repeal of the law would require the standard consitutional cooperation between the White House and Congress--ostensibly requiring suffcient partisan concurrence in order to be effected.