[Q...] But is it legal for the president to ignore the law?
A. Maybe not according to plain ol stupid ol regular law, but we're at war! You don't go to war with regular laws, which are made outta red tape and bureaucracy and Neville Chamberlain. You go to war with great big strapping War Laws made outta tanks and cold hard steel and the American Fightin Man and WAR, KABOOOOOOM!
Q. How does a War Bill become a War Law?
A. It all begins with the president, who submits a bill to the president. If a majority of both the president and the president approve the bill, then it passes on to the president, who may veto it or sign it into law. And even then the president can override himself with a two-thirds vote.