A year ago this month, President Obama announced his intention to launch military strikes against the regime of Syrian President Bashar al-Assad, who had crossed a "red line" by using chemical weapons against his own people. There was just one hitch: Congress, which is the only branch of government with the authority to declare war, would have to approve the operation first. "While I believe I have the authority to carry out this action without specific congressional authorization," Obama said, "our country will be stronger if we take this course."

Many politicians at the time agreed. Many, in fact, had criticized Obama for launching unilateral strikes against the regime of Libyan dictator Moammar Gadhafi in 2011. The criticism came from both sides of the aisle, larded with proclamations about preserving the integrity of the Constitution. "When there is no imminent threat to our country, he cannot launch strikes without authorization from the American people, through our elected representatives in Congress," said Rep. Justin Amash (R-Mich.), speaking for many. "No United Nations resolution or congressional act permits the president to circumvent the Constitution."

What a difference a few years make.

As the U.S. rains bombs on the Islamic State of Iraq and Syria — expanding an operation that began as a limited, humanitarian mission to protect persecuted Yazidis and American personnel — lawmakers have been awfully quiet about the whole business of congressional authorization.

"[T]here has been no such collective insistence from members of Congress that they should approve Obama's limited airstrikes on [ISIS] targets," John T. Bennett recently noted in Defense News. "In fact, on the matter of signing off on the strikes, lawmakers have been surprisingly silent."

There have been exceptions. And there are those who, like Rep. Peter King (R-N.Y.), believe Obama is well within his power to launch strikes against ISIS or anyone else without congressional approval.

But as American voters absorb the brutal murder of journalist James Foley at the hands of ISIS, Congress appears willing to give Obama free rein to attack the extremist group as he sees fit. That includes helping Iraqi and Kurdish forces secure dams and generally weaken ISIS, operations that very much look like what a country does during war.

From a political perspective, there are a couple explanations for Congress' newfound appreciation for deferring to the White House. For one, the attacks on ISIS are only growing in popularity, which means lawmakers can act as tough as they want from the sidelines without binding themselves to a particular policy with a vote.

That gets to the larger issue. It's helpful to remember that the Syria vote looked like it was heading toward disaster before it was preempted in the 11th hour by a John Kerry gaffe and some wily Russian maneuvering. Democrats, under pressure to help Obama save face, were stuck with the prospect of authorizing yet another military intervention in the Middle East — a vote that would have been held against them if the strikes went awry. Republicans, meanwhile, were torn between their desire for stronger military action and the repellant idea of siding with Obama, which essentially would have been like voting for a primary challenge against themselves.

It has become a cliche to speak of Congress abdicating its responsibility. But the case of ISIS is particularly instructive in showing congressional evasion in its most naked form. Setting aside the legal merits of Obama's actions, it is clear that there are many lawmakers who wouldn't mind switching their position on the issue of the president's ability to unilaterally launch strikes against perceived enemies — all because they simply don't want to vote on it.

Congress, particularly the GOP-controlled House, is such a mess, such a pit of vacuous posturing and newstainment controversies, that many voters will be happy to see it sit this one out. But that doesn't change the fact that this inaction by lawmakers, this exercise in plausible deniability, is the very definition of not taking responsibility — for governance of the country, yes, but also for their own political convictions (presuming such convictions even exist).

The 2014 elections are around the corner, which means politicians can arguably be forgiven for lying low. The problem is that this dynamic is constant — touching other issues like immigration reform — turning the simple act of casting a vote into one of the most perilous moves a politician can make. ISIS shows that the problem of congressional paralysis isn't a lack of agreement between the two parties, but a paranoid political culture that discourages voting on any legislation that carries even minor risk.

President Obama is often chided by a certain class of political pundit for failing to demonstrate that nebulously defined quality called leadership. But the truth is that the president is one of the few people in Washington willing to even make a decision — and to take the heat for it.