War powers act strengthen the influence of the legislative body in determining when united states can be involved in war
Before the war power acts, the right to initiate war fall solely to the hand of the president (which is the head of the executive branch).
After the war power act, the president could no longer initiate a war unless the president manage to get permission from the Congress (part of legislative body) . This make the legislative body has more influence in initiating the war than the president.