Experts: Obama's walking a fine line legally with these Iraq strikes

Most constitutional law experts say Obama acted within his authority to defend Americans in Erbil from immediate danger. But critics say Obama should have sought congressional approval before expanding a fight with ISIS that could last months or even years.

“I think any conflict of a couple days in nature could be justified,” said Louis Fisher, a scholar at the Constitutional Law Project, “but as President Obama said last weekend, this is not going to be for just a couple days or weeks, it could go on for a year or two.

“For anything of that scope, he should come to Congress for their approval,” Fisher added.

Fischer and other constitutional scholars believe Obama is toeing a fine line by engaging ISIS forces in Iraq.

“Defensive power is limited to an immediate response to an attack,” said Peter Raven-Hansen, a national security professor at George Washington University’s law school.