Every US Executive Branch since passage of the US WPR has refused to acknowledge that the WPR is constitutional. All US Presidents have ignore it and some (including their justice department) expressly state the law is unconsititutional.
Typically the Supreme Court avoids becoming involved in these types of disputes between the executive and legislative branches (citing the political question doctrine to refuse to hear such cases) and instead leave resolution of such a dispute between executive and legislative branches to the political process. Below is an interesting paper discussing the judicial role in the dispute between the executive and legislative branches regarding the consitutionality of the War Powers Resolution.
http://scholar.valpo.edu/cgi/viewcontent.[WORD TOO LONG]
"The issue then becomes whether legislation restricting executive power such as the War Powers Resolution is an effective exercise of constitutional power. This predicament necessitates the interpretation of the Constitution, and the inherent conflicts in the provisions supplying the president and Congress with their respective war power. In this situation, the Supreme Court retains the authority to interpret the Constitution.
However, the Court appears reluctant to become involved in disputes between the other two branches and uses the political question doctrine as a means to avoid reaching the merits of the disputes."
The author concludes that the Court should get inolved and rule against the Executive Branch where needed:
"The constitutional division of the war power between the executive and legislative branches can cause an inherent conflict when one branch exercises its power in opposition of the other. While the Supreme Court would typically find such a conflict nonjusticiable under the political question doctrine, the Court should find these disputes cognizable if the president oversteps the breadth of his constitutional authority impeding upon the power attributed to another branch . . . "
Since 1973, United States Presidents have been required, by law, to seek Congressional approval prior to making use of the United States Armed Forces in any action or conflict. Recognizing that there are circumstances where such prior approval will be impossible, Congress specified that no approval is required for a national emergency created by attack upon the United States, its territories or possessions, or its armed forces. (50 USCS § 1541(c)(3)). However, Barack Obama has now entered the United States Military into an action against Libya which lacks either Congressional approval or a specific threat to the United States. It is open regarding the War Powers Resolution and what action, if any, may be taken in response to a violation of the Resolution.
The Constitution provides that war powers are divided between Congress and the Executive Branch. The war powers of the United States Congress are as follows:
To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water;
To raise and support Armies, but no Appropriation of Money to that Use shall be for a longer Term than two Years;
To provide and maintain a Navy;
To make Rules for the Government and Regulation of the land and naval Forces.
(Constitution of the United States: Article 1, Section 8.)
The Presidential war powers are as follows:
The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States. (Constitution of the United States: Article 2, Section 2.)
Congress, in determining that the necessary and proper clause permitted clarification of the interworking of the war powers of the legislative and executive branches of government, passed the War Powers Resolution (50 U.S.C. 1541-1548). This resolution was enacted into law on November 7, 1973, by a two-thirds vote in each house of Congress, which overrode then President Nixons veto.
In February, 2011, Muammar Gaddafi began to attack many of his own people who had organized an opposition to him. After a lengthy delay, Mr. Obama responded by, on March 19, 2011, engaging the United States in a military action against the Libyan Government. Mr. Obama gave as justification for this action provisions under the War Powers Resolution, specifically to protect civilians from being harmed by Muammar Gaddafi, even though the justification did not satisfy the grounds of threat to the United States under the Resolution.
Even though many Members of Congress supported the use of the United States armed forces against the Libyan Government, and Congress presumably would have approved the same if asked to do so, Barack Obama failed to seek any approval from Congress to authorize the action, either prior to the beginning of the campaign against Libya, or during the 60 days following, as required under the War Powers Resolution.
Congress has done nothing about this blatant disregard of the War Powers Resolution. Certain Members of Congress have expressed their disapproval of the Mr. Obama's actions, particularly in not seeking their approval, but Congress has not, as of the date of this report, taken any significant steps to end the action in Libya. In effect, the United States Congress has treated the contents of the War Powers Resolution as if they are non-binding suggestions to the Executive Branch.
In an effort to avoid the authorization requirements of the War Powers Resolution, Mr. Obama transferred the command of this action against the Libyan Government to NATO, and declared that the United States was not "majorly involved."€It must be noted that despite NATO being an international alliance, it is, effectively, controlled and directed by the United States, as the United States provides a majority of the resources and the troops serving under the NATO banner.
On May 20, 2011, after the 60 day deadline under the War Powers Resolution had passed, Mr. Obama sent a letter to Congress asking for authorization for the action in Libya. He concluded the letter by saying:
"Congressional action in support of the mission would underline the U.S. commitment to this remarkable international effort. Such a Resolution is also important in the context of our constitutional framework, as it would demonstrate a unity of purpose among the political branches on this important national security matter. It has always been my view that it is better to take military action, even in limited actions such as this, with Congressional engagement, consultation, and support." (http://www.nytimes.com/2011/05/21/world/africa/21libya-text.html?_r=3&ref=libya)
The War Powers Resolution has long been thought to be unconstitutional, particularly with regards to the provision in 50 USCS § 15449(c), which gives Congress a legislative veto over executive use of the military that Congress does not approve. This was discussed in the dissent of Justice White in the case of INS v. Chadha (462 U.S. 919 [1983]). In that case, the United States Supreme Court held that a legislative veto by one house of Congress was unconstitutional (462 U.S. 919). While the issue of an improper legislative veto by a joint resolution of both houses of Congress was not resolved in the majority's decision, Justice White, in his dissent, discussed that such a veto by joint resolution would also be unconstitutional (462 U.S. 919, 971 [1983]). Even though this suspected unconstitutionality has not yet been resolved by the courts, it seems likely that the courts would so hold if the matter were to be brought before the courts.
Because Barack Obama did not comply with the provisions of the War Powers Resolution, his actions constitute an ongoing violation of United States statute, and, although Congress could even now authorize the continuation of the military action in Libya, they have not yet done so. Since Mr. Obama has violated a United States statute, the question is what may be done about that violation. Ideally, Congress should use its authority to authorize the action, to force Mr. Obama to comply with the War Powers Resolution, or to end the military campaign. However, since Congress seems unwilling to assert their authority in this matter, a lawsuit may be necessary to enforce the law.
The difficulty with bringing a lawsuit to enforce this resolution is that the courts are very reluctant to either review or to resolve conflicts between the legislative and executive branches in separation of powers matters, and, in particular, with matters concerning war which are, by their nature, political questions outside the review of the court. As already discussed, the Constitution divides the war powers between the legislative and executive branches, which invites separation of powers issues, such as the War Powers Resolution purports to address.
In past cases concerning this law, the courts have been very reluctant to hear them at all, let alone make a determination as to whether the law is constitutional:
"Action brought by 26 members of U.S. House of Representatives seeking declaration that President has violated War Powers Resolution (50 USCS §§ 1541 et seq.) in assisting air offensive against Yugoslavia is dismissed for lack of standing, where various and inconsistent votes show at most that Congress is divided about its position on President’s actions and President has continued with air strikes in face of that divide, because, absent clear impasse between executive and legislative branches, resort to judicial branch is inappropriate."€ Campbell v Clinton (1999, DC Dist Col) 52 F Supp 2d 34, affd (2000, App DC) 340 US App DC 149, 203 F3d 19, cert den (2000) 531 US 815, 148 L Ed 2d 19, 121 S Ct 50.
Congressmen lacked standing to challenge President’s action in directing U.S. forces’ participation in NATO campaign in Yugoslavia as violation of war powers resolution and war powers clause of Constitution, since their dispute was susceptible of political resolution; Congress has broad range of legislative authority it can use to stop President’s war making. Campbell v Clinton (2000, App DC) 340 US App DC 149, 203 F3d 19, cert den (2000) 531 US 815, 148 L Ed 2d 19, 121 S Ct 50.
Based on these cases, in order for a lawsuit on the War Powers Resolution to be successful, it will have to be shown that there is a clear impasse between the executive and legislative branches, and that Congress has at least attempted to use its authority to stop the President's action. A clear impasse is not shown simply because a number of the members of Congress have grumbled against Mr. Obama's action, and, unless Congress takes some steps in opposing his violation of this Resolution, it is likely that any lawsuit on this statute will be dismissed due to a lack of standing.