Since 2001, US presidents have treated the War Powers Act of 1973 as very much optional. The law, which requires specific Congressional authorization for US military operations, has been openly ignored by officials, who claim the vague 2001 Authorization for the Use of Military Force (AUMF) passed after 9/11 lets the president do whatever he wants.
The 2001 AUMF isn’t as vague as presidents have presented it, of course. The language is very clear about authorizing war against those involved in 9/11, and al-Qaeda in particular. Still, it’s been used as a pretext for wars across the planet with obviously nothing to do with al-Qaeda, from involvement in Yemen or the Libya regime change.
Congress has been so neglectful in enforcing the War Powers Act with respect to this AUMF, however, and the Justice Department has insisted courts aren’t even allowed to question it, that many in Congress are suggesting the 2001 AUMF be scrapped outright, and new war, more specific war authorizations, be voted on.
Attempts to try to force votes in Congress on War Powers Act violations have been difficult, with the House leadership resisting an upcoming hope on the Yemen War never having been authorized. Eliminating the 2001 AUMF would remove even the pretense of legality.
The revelation that the US is at war in Niger, without Congress even knowing, is adding to the sense among many lawmakers that they really need to get a handle on this whole war thing, if they want to even pretend to have their Constitutionally assigned war-making powers.
The idea of replacing the 2001 AUMF with specific AUMFs with obvious limitations is being loudly opposed by the Trump Administration, which insists that such limitations don’t make sense in the era of “non-traditional” warfare.
Secretary of Defense James Mattis says wars are so unpredictable at this point, that things like restricting them to specific enemies or borders or time-frames, and claimed the wars would be over sooner if Congress just let the military fight its “enemies.”
Even who the enemies are at this point is never publicly stated, and President Trump has been very public about having delegated war-making authority to top military generals, who appear to be able to manufacture entire conflicts like Niger with neither the oversight of Congress or even their knowledge.
Secretary of State Rex Tillerson insists that the 2001 AUMF gives the executive branch all the authority they need for all of these wars, and that seems to be something the rest of the president’s aides are comfortable with remaining the case.
If Congress is ever going to limit war-making again, it’s going to be a big fight with the administration, as they aren’t going to easily give up their carte blanche to start wars worldwide.