The problem isn't really with the law, it is with the apparent ambiguity in the constitution: at what point does the power of the commander in chief to direct the military meet the necessity to have a declaration of war before directing engaging military operations. The presidential assertions of power to control that absolutely have rendered the notion of “declaring war” moot. While it is possible that some of that could be adjudicated at the Supreme Court, or by use of impeachment to set precedent for future presidents on what the congressional limits are, or by congress writing language in appropriations bills that prevent money from being used for offensive military purposes, they would only approximate an answer.
The only way to eliminate the ambiguity would be to define by means of a constitutional amendment what a “war” is that needs a congressional declaration and what types of military operations do not and are at the president's discretion. Such an amendment would probably have to spell out what is meant by “commander in chief” as well. Something based on the notion that that the commander in chief shall direct the operations of the military in peace, or for either immediate defensive purposes or after a congressional declaration of war both subject to the definition of a “significant military action” (per below) and that no monies are to be used except subject to these conditions. (The final part is to be clear that there isn't an implicit “turning over” of funds to the president that can be redirected to an undeclared war, and providing another standard for impeachment if need be.)
Re: Obama to Hear Panel on Changes to War Powers Act:
... Mr. Obama plans to meet Thursday with the leaders of a commission that has proposed revamping the legal process for launching military action, to require more consultation between a president and Congress.
The proposal would scrap the problematic War Powers Act of 1973, a measure passed in the hangover from Vietnam to give Congress more say in committing troops to the battlefield but largely honored in the breach ever since by presidents who deemed it unconstitutional. In its place, the commission proposes a law requiring a president to consult lawmakers before any “significant military action” and calling on Congress to vote up or down within 30 days.
The Constitution divides war powers between the executive and legislative branches. Article I gives Congress the authority to “declare war” and finance military operations while Article II makes the president the “commander in chief.” As a practical matter, though, the balance has tilted increasingly toward presidents, particularly in the last half century as the world has grown more complicated, dangerous and national security threats more fast moving.
A president would have to consult with Congress before any “significant military action” expected to last more than a week or within three days of the start of action in circumstances where secrecy is paramount. This would not include short-term missions such as protection of United States embassies, reprisals against terrorist attacks or covert operations.