Senate Democrats moved Thursday to drastically change the chamber's rules in what's known as the "nuclear option" — the last resort plan that they felt they had to do.

Why did they do it? To make it so that executive and judicial nominees are ensured an up-or-down vote on their nomination. Senate Majority Leader Harry Reid, along with other Democrats who have been skittish about relinquishing minority power in the past, felt there was no other choice.

Not doing so, Democrats feel, would set up a terrible precedent — that a minority group of senators could try to control the ideological balance of the courts while preventing the president from fulfilling one of his constitutional responsibilities.

The rules change is a huge victory for President Barack Obama, much like the last fight over the "nuclear option" was last summer. Most likely, three of his nominees to the powerful U.S. Court of Appeals for the D.C. Circuit — Patricia Millett, Nina Pillard, and Robert Wilkins — will be confirmed.

This is significant for Obama's second-term agenda, which, so far, has been stalled by a filibuster-happy Republican Party in Congress. Many of Obama's appointees are controlling his agenda, writing new rules for financial reform, climate change, even gun control and immigration.

The new rules change might end up being the most important part of Obama's legacy outside of Obamacare. The D.C. Circuit Court, outside of the Supreme Court, is generally considered the second most powerful court in the nation, with its vast jurisdiction over the federal government and thousands of regulations, rules, and executive actions from more than 400 administrative agencies. It's the court, for example, that in January ruled Obama's 2011 recess appointments unconstitutional.

"The issues before this court are some of the most important with respect to administrative law, which is where so much law gets made today," Roger Pilon, the chair of the Cato Institute's Center for Constitutional Studies, told Business Insider.

"When you can't get things through Congress in the normal, constitutional way, what you do is exactly what Obama's doing," he said. "You turn to ruling by executive order."

One of the key tenets of Obama's second-term agenda is in the area of climate change, on which he has no chance of working with Congress. He has admitted this, and so the Environmental Protection Agency has been writing new rules on climate policy, including new carbon emissions standards for existing power plants.

Any challenges to Obama's new policies could end up in the D.C. Circuit Court. If Obama's three nominations are confirmed, it will be composed of seven Democratic president-appointed judges and four Republican president-appointed judges. Five of the six "senior" judges who work part-time on case overloads were appointed by Republican presidents.

Senate Republicans argued that the D.C. Circuit Court's workload didn't require more judges. They pointed to the fact that the court regularly cancels sittings because there aren't enough oral arguments for judges to hear.

"The Administrative Office of the U.S. Courts determines by strict formula what constitutes a judicial emergency, not some 20-something Dem press secretary who doesn’t know a circuit breaker from a circuit court," a Republican Senate aide told Business Insider. "According to the non-partisan arbiter, the D.C. Circuit doesn’t even come close to being an emergency."

But with the apparent short-term boon for Obama and Democrats comes risk — namely, in that a year from now, Senate Democrats could find themselves in the minority. Senate Minority Mitch McConnell warned of that possibility on Thursday, repeatedly telling Reid and Democrats on the Senate floor that they would "regret" the rules change.

Make no mistake: Reid's move Thursday is a signal of faith in Democrats holding onto their Senate majority in 2014. If they don't, it provides a slippery slope for Republicans to get rid of the filibuster for good next year.

But Democrats also believe Thursday's rules change was a long time coming — and its importance in allowing the government to function can't be overstated.

"The Senate functioning is important regardless of electoral consequences," one senior Democratic strategist told Business Insider.