Supreme Court Justice Ruth Bader Ginsburg said she opposes proposals by many 2020 Democratic hopefuls to expand the Supreme Court or to place term limits on federal judges.

"Nine seems to be a good number. It's been that way for a long time," she told NPR. "I think it was a bad idea when President Franklin Roosevelt tried to pack the court."

On the subject of term limits, Ginsburg said she is not worried about anything changing, because "our Constitution is powerfully hard to amend."

The most popular of the proposals to change the structure of the Supreme Court would require expansion from nine to 15 justices. Democrats in the Senate would choose five, Republicans would choose five, and together those 10 justices would pick another five, in a vote independent of the people who picked them. This plan is backed by former representative Beto O'Rourke and South Bend mayor Pete Buttigieg, who are both running for president.

Ginsburg said this is a harmful plan because it would give the court the appearance of politicization.

"If anything would make the court look partisan," she said, "it would be that — one side saying, ‘When we're in power, we're going to enlarge the number of judges, so we would have more people who would vote the way we want them to.'"

Ginsburg went on to praise the current state of the United States' judiciary.

"We are blessed in the way no other judiciary is in the world is," she said. "We have life tenure. The only way to get rid of a federal judge is by impeachment. Congress can't retaliate by reducing our salary, so the safeguards for judicial independence in this country, I think, are as great or greater than any place else in the world."

Ginsburg also noted that in her opinion, the Court's opinion is not a final authority on the Constitution, and relies on public trust to retain its power.

"The court has no troops at its command," Ginsburg said, "doesn't have the power of the purse, and yet time and again, when the courts say something, people accept it."