Lawmakers were not notified of the Guantanamo detainees’ transfer until after it occurred.
The law requires the defense secretary to notify relevant congressional committees at least 30 days before making any transfers of prisoners, to explain the reason and to provide assurances that those released would not be in a position to reengage in activities that could threaten the United States or its interests.
Before the current law was enacted at the end of last year, the conditions were even more stringent. However, the administration and some Democrats had pressed for them to be loosened, in part to give them more flexibility to negotiate for Bergdahl’s release.
I read that at the time of signing the law, Obama issued a “signing statement” saying essentially that he disagreed with it and did not consider it binding on him.