US President Barack Obama’s choice to go to Congress for approval of his decision to take military action against Syria is just another chapter in a never-ending battle between American presidents and Congress. The fray is over the question: can a president use military force solely on his own authority? Though the controversy could be traced back to the founding of the US, the modern fight dates back to the 1973 War Powers Resolution passed by Congress in the shadow of the Vietnam War to give a concrete way to hold presidents back from getting too deep into an unpopular war without transparency and checks from Congress. The resolution allows a president to take unilateral military action without Congress formally declaring war. But more importantly, it requires the president to report on the action within 48 hours and to withdraw forces between 60-90 days after the action has started, if by 60 days the president has not obtained Congressional approval.Every American president has stated their belief that the resolution is an unconstitutional restriction on their inherent powers as Commander- in-Chief.The US Constitution does not specifically list a presidential power to order military action short of total war without Congressional authorization.Still, every president has said that because the president is Commander-in-Chief entrusted with defending and securing the country, by definition, the executive must possess the power to order such actions on his own in the face of threats that move faster than Congress can operate.Congress has claimed the resolution is constitutional on the basis of its authority to declare war, to legislate all issues necessary and proper to the running of the country, its power over funding the military and its role in maintaining the armed forces (the Constitution does not mention an air force, but everyone agrees that its intent would have included an air force in the modern context).Former presidents Ronald Reagan and Bill Clinton fought over application of the resolution and both of them flouted its restraints where they believed necessary.Reagan clandestinely aided the Contras militarily in Nicaragua in 1985-1986, while Clinton ignored Congress in bombing Kosovo in 1999.Both had fights over the issue, and members of Congress have sued presidents, most notably in the 2000 Campbell case, where a US court said that the issue is beyond the authority of the courts to decide, since courts are not equipped to define “war” versus “hostilities,” who started a war and other critical questions.So the courts will not decide the issue.Obama himself fought in 2011 over his military action in Libya when it continued for more than 60 days without consulting Congress.Congress “rebuked” Obama 268-145 for the lack of consultation, but Obama said that at that point he had handed running of the armed conflict over to NATO, so that the 60 days no longer applied.Presidents have sought Congressional authorization for military action as George H.W. Bush sought for the 1991 Iraq War and George W. Bush sought for the 2003 Iraq War, but both undertook other actions for which they did not seek authorization or were accused of being misleading in seeking authorization.In general, like many conflicts between different branches of government, the politics of the moment cannot be separated from the legal disputes.While some have said that Obama may have a stronger affinity to constitutional limitations on presidential powers as a former law professor, the hard facts are that where military action is popular and considered critical to self-defense, presidents feel less pressure to consult and Congressional anger at being ignored is not likely to register with the public.Where action is unpopular, as in Syria, and the basis for action is more amorphous than self-defense, such as to send a message about chemical weapons use or for humanitarian reasons, presidents, whether Obama or others, are more likely to feel the political and legal pressures to consult Congress, even as they say that the consultation is voluntary and unnecessary.