President Obama’s decision to consult Congress about striking Syria brought him in line with the War Powers Resolution, a 1970s statute that both he and his White House predecessors have defied, epitomizing a broader constitutional clash about executive authority and the definition of combat.

Since World War II, presidents including Obama have seized a greater amount of control over military engagements, initiating foreign conflicts without even trying to obtain approval from Capitol Hill. Obama’s appeal to Congress will hardly quell a raging debate about the scope of executive reach.

Codified in 1973, the War Powers Resolution says the president can initiate an armed conflict only after a declaration of war, with a specific authorization, or during an attack on the U.S. or its territories. As stated in the Constitution, Congress alone has the authority to declare war.

Presidents have paid a heavy political price for entering military conflicts without a clear congressional stamp of approval, a reality certainly not lost on Obama as he calls for strikes that lack broad public support.

President Harry Truman never received a declaration of war to invade Korea — even though the measure had widespread congressional support — and his approval ratings tumbled because of the extended intervention. Truman’s method for circumventing Congress was to call the military response a “police action” rather than an act of war.

After the Gulf of Tonkin incident, Democratic President Lyndon Johnson launched the Vietnam War, initiating a clash that killed more than 58,000 Americans — without explicit approval from lawmakers for such open-ended warfare. Troops were sent in under the auspices of “military advisers.”

Looking to correct what they viewed as executive overreach in the Vietnam War, lawmakers in 1973 believed the War Powers Resolution would slow the growing tendency by the White House to launch military conflicts without engaging Congress.

The law did little, however, to lessen presidential pursuits of wartime powers.

“I think the text is pretty clear, but it’s also clear that presidents have chafed at its constraints,” George Mason University law professor Ilya Somin said of the War Powers Resolution. “They argue that it’s unconstitutional. But they only have that authority with an operation so small that it doesn’t qualify as a war.”

Recent presidents have argued the resolution undermines their responsibility as commander-in-chief to protect the homeland.

Then-candidate Obama ripped such presidential interpretations of the law.

“History has shown us time and again, however, that military action is most successful when it is authorized and supported by the legislative branch,” Obama said in 2007. "It is always preferable to have the informed consent of Congress prior to any military action.”

He sang a different tune after becoming commander-in-chief. He launched an air strike in Libya two years ago, despite never receiving congressional approval. The president said that because NATO took control of the operations and that U.S. troops were not on the ground, he was within his authority to pursue unilateral action.

Similarly, President Bill Clinton in 1999 initiated bombings in Kosovo, never consulting Congress. The White House argued it didn’t need to reach out to lawmakers since the operation was completed within the 90-day timeline outlined by the War Powers Resolution.

President Ronald Reagan in 1983 invaded Grenada in an effort to push aside the Cuban-supported government there. He never sought permission from Congress.

Generally speaking, recent presidents have sought congressional approval for lengthy military operations and have claimed executive authority when pursuing more limited engagements. President George W. Bush was given the go-ahead by lawmakers for the Iraq and Afghanistan wars, and President George H.W. Bush received congressional backing for the Gulf War.

What such White House precedent portends for U.S. policy in Syria remains to be seen. Democratic senators are drafting a resolution that would limit the duration and extent of military involvement in Syria, which were left intentionally vague in the framework sent by administration officials to Capitol Hill.

But some said Obama has limited options if Congress rejects his call for intervention in the civil war there.

“It would be politically really hard to go to Congress, get a vote and ignore the vote,” Somin said of Obama’s Syria pitch. “That would be a dangerous and risky thing to do.”