Why have presidents since 1973 disagree with the requirements of the war powers act passed by congress?

Thesis statement for negative effects on immigration

The military dictatorship inviolently reacted to the opposition of the maya, who demanded greater rights for their native population. the genocide inresulted from a struggle between arab nomadic tribes and non-arab agricultural groups. the tutsi were the victims of genocide inat the hands of the hutu rulers.

Which type of constitutional power allows congress to regulate immigration and naturalization?