Does the Department of Justice HAVE to Defend Every Law?

One head line this morning was that serial adulterer Newt Gingrich wants to impeach Obama for not defending section 3 of the Defence of Marriage Act which states that the federal government defines marriage as a legal union between one man and one woman.

His rant when on to say,  "His job is to enforce the rule of law and for us to start replacing the rule of law with the rule of Obama is a very dangerous precedent.".

 Well I had a feeling he was wrong and so did many others so it did not take long to find examples of when the DOJ has refused to defend other laws.

It is tactics like this that are abused by some to misinform people about issues to sway them to their side. Newt maybe running for president in 2012 and I would not want a 3 time adulterer and misinformer to be running the country.

This is part of a larger article that best answered my questions.

Exerpt from Queerty

Then how come the Justice Department's history is riddled with examples of this "defend laws at all costs" mantra … not being true?

In fact, the very man who argued DoJ doesn't have to defend every law on the books is a man named John Roberts. You might know him, now, as the chief justice of the Supreme Court. But back in 1990, when he was a DoJ attorney, Roberts "was the point person in the Office of the Solicitor General in 1990 when that office decided not to defend the constitutionality of federal statutes that required minority preferences in broadcast licensing," wrote former Clinton administration DoJ counsel Marty Lederman in 2005; Lederman is now a deputy assistant attorney general to President Obama. Continues Lederman (read this):

As a general matter, the Department has traditionally adhered to a policy of defending the constitutionality of federal enactments whenever "reasonable" arguments can be made in support of such statutes — i.e., whenever the constitutionality of the law is not fairly precluded by clear constitutional language or governing Supreme Court case law. This practice has been predicated on the notion that because the political branches — the Congress that voted for the law and the President who signed it — have already concluded that the statute was constitutional, it would be inappropriate for DOJ lawyers to take it upon themselves to reject the constitutional judgment shared by the President and the legislature.
There are, however, historical exceptions to this general practice. Almost all of the exceptions fall into one of three categories. The first category is cases in which intervening Supreme Court decisions have rendered the defense of the statute untenable. This category isn't really an "exception" to the "rule" as much as it is an illustration of how the rule operates in practice: The newly governing Supreme Court decision eliminates any reasonable argument that might have been made in the statute's defense, other than asking the Court to overrule its governing precedent (a tactic that the SG very rarely employs, but that is not unheard of, as in the second flag-burning case (Eichman), and in Agostini v. Felton). The second category involves statutes that in DOJ's view infringe the constitutional powers of the President himself (e.g., Chadha; Bowsher v. Synar). The third, and smallest, category involves statutes that the President has publicly condemned as unconstitutional. The most famous such case was probably U.S. v. Lovett, in 1946. More recently, after the first President Bush vetoed the "must-carry" provisions of a cable television bill on constitutional grounds and Congress overrode the veto, the Bush (41) Administration declined to defend the constitutionality of the must-carry provisions. (The Clinton Administration reversed this decision and subsequently prevailed in its defense of the law in the Supreme Court in the Turner Broadcasting litigation.)