
Congress can't really declare a War anymore...
Because many loan and insurance documents contain legal language with the phrase "Act of War".
If a war is declared many insurance policies are null and void. Insurers can't insure for war, banks and finance companies cannot loan money if insurance can't be obtained.
Heck, some bank/finance companies may even hold the right to demand notes be paid off at the declaration of war.
So, I think the reason no war has been declared since 1941 is because we owe too much money, and we can't afford the consequences.