The careers of Supreme Court justices often far outlast those of the presidents who appoint them.

While a president can typically influence the course of government for four or eight years, it's not unusual for a justice to work for decades.

Even Franklin D. Roosevelt, who served a record-setting 12 years as president, pales in comparison to the eight Supreme Court justices he successfully nominated.

They ended up serving a total of 143 years, the most of any single president's judges.

A study of Supreme Court service by Congress.org found two other presidents whose appointees shaped the court for more than a century: Andrew Jackson and Abraham Lincoln.

At the other end of the spectrum, four presidents never got a chance to appoint anyone: William Henry Harrison, Zachary Taylor, Andrew Johnson and Jimmy Carter.

John Q. Adams, meantime, saw his sole appointee die of a fever after just two years on the court.

To be fair, looking at Supreme Court influence simply by years of service is a crude measurement. Justice Benjamin Cardozo, widely recognized as one of the finest legal minds to sit on the court, served just six years.

And President Gerald Ford was extremely proud of his lone appointment, John Paul Stevens, who in his 35 years on the court has become a leading liberal voice.

But nominations have increasingly become a numbers game, with Presidents George W. Bush and Barack Obama explicitly looking for younger nominees in order to increase their odds of having a lasting impact on the court.

"Every president wants to put their stamp on the Court as much as possible," University of Missouri Law Professor Richard Reuben said.

President Obama currently ranks just below Adams, with less than a year of influence. But with two justices on the court, he would surpass the median of 34 years of influence by 2027.

Age wasn't always an important factor in Supreme Court nominations.

George Washington, who appointed the first nine justices and some of their replacements, made his picks from among his peers. Several served less than a year.

Reuben, who covered the Supreme Court for the American Bar Association Journal, said that the job was viewed differently in the past.

"Serving on the Supreme Court used to be the height of your career," he said. "Now the time justices spend on the court tends to be their most productive years."

Presidents haven't always been thrilled with their picks either. It was widely reported that Eisenhower thought he erred in picking Justices Earl Warren and William J. Brennan Jr.

And presidents have no influence over justices after they're appointed.

Some conservatives were disappointed in what they viewed as the late-blooming liberal tendencies of Justice David Souter, who was appointed by Republican President George H.W. Bush.

Beyond years, Obama faces a particular challenge if his goal is to reshape the court.

Many of the conservatives on today's Supreme Court are young while those retiring are liberals. Obama could maintain status quo by replacing them with liberals, or he could even tilt the court to the right by swapping in centrists, Reuben argued.

"Barring the unforeseen, the best that Obama can do is regenerate the left side of the Court," he said.

Ambreen Ali writes for Congress.org.

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