President Obama will conduct the American military action against ISIS as vigorously or (more likely) as halfheartedly as he desires. This is true whether or not Congress passes a new military authorization.
Why, then, does Obama seek an anti-ISIS authorization for the use of military force. For two reasons, I believe: (1) for political cover and (2) to constrain his successor.
The authorization Obama seeks does not authorize “the use of the United States Armed Forces in enduring offensive ground operations.” If passed, therefore, the authorization would provide political cover for Obama to resist pressure to use U.S. ground troops in a sustained and serious manner.
The authorization might also constrain the next president if he or she wished to use ground troops to take the fight to ISIS. Obama’s successor would face the argument that the president lacks authority to do so.
In addition, once the authorization expired, early in the next president’s term, Obama’s successor would be under pressure to seek a new authorization. If, on the other hand, no authorization is passed, the presumption will be that the next president can do what he or she pleases, as Obama has done.
Accordingly, my preliminary view is that Congress should reject the authorization that Obama has requested.