It’s a bipartisan problem. Barack Obama, whose political star rose due to his opposition to the Iraq war, was perhaps our worst offender, circumventing Congress and relying on a decade-old AUMF, which he invoked 19 times during his presidency, to justify a half-hearted intervention against ISIS (not al-Qaeda) in Syria (not Afghanistan.)
Trump could bomb Iran tomorrow, use Obama’s reasoning, and have a far stronger legal defense for his actions.
It was also Obama who joined Europeans in the failed intervention in Libya, where he worked under NATO goals rather than the United States law. There was hardly a peep from Democrats fretting over the corrosion of the Constitution.
Republicans too were given ample chance to sign-off on Syrian intervention in 2013 when Obama, fully aware of congressional aversion to accountability, asked for a new AUMF to get out of bombing Assad. It would have been a great time for senators to dictate long-term goals in Syria. It’s not too late. If they believe Trump’s strategy is wrong, they can still force his hand by explaining the mission with a new AUMF. Let’s see if voters agree.