As President Trump and the Senate prepare to quickly fill the Supreme Court seat vacated by the death of liberal Justice Ruth Bader Ginsburg with a conservative judge, Amy Coney Barrett, Democrats are discussing the possibility of "packing" the court, should November's voters give them control over the White House and both houses of Congress.

Some critics argue that adding seats to the court, in an effort to diminish or reverse its conservative majority, would mean abandoning a longstanding norm against court packing. In recent years at the state level, however, some Republican politicians have already abandoned such norms.

And it's not as if norms around picking federal judges haven't eroded at the federal level. Both Democrats and Republicans eliminated the Senate filibuster for certain judicial appointments, after complaining about obstructionism by senators from the other party. And in 2016 and 2017, the Republican-led Senate left a Supreme Court seat vacant for a year, refusing to hold a vote on President Barack Obama's nominee.

But norms have eroded even further at the state level. In Florida, Iowa and other states, Republican legislatures have changed the rules for judicial nominating commissions to give governors more control. High-court justices have been threatened with impeachment for issuing rulings that legislatures didn't like.

Some Republican legislatures also have added seats to their states' supreme courts to create new conservative majorities that are still in power today. In 2016, for example, Republicans in Georgia added two seats to the state Supreme Court to create a new conservative majority, giving GOP Gov. Nathan Deal two appointments.

Republicans in Arizona did the same thing that year, adding two high-court seats to allow GOP Gov. Doug Ducey's appointments to create a new conservative majority. Ducey then manipulated the Arizona Constitution's rules for appointing the state's judicial nominating commission in an effort to push the court further to the right.

Around the same time, Republican legislators in North Carolina floated the idea of adding two seats to their state's Supreme Court. The suggestion came during a December 2016 lame-duck session, just weeks after voters had elected a new progressive majority to the high court along with a Democratic governor. This court packing plan led to protests and criticism from across the ideological spectrum, since it would have undone the results of the election. Legislators didn't follow through.

In 2018, however, the North Carolina Legislature passed a constitutional amendment that could have opened the door to a different court-packing scheme. The amendment would have given legislators control over choosing judges to fill vacant seats. When a Democratic legislator asked if their goal was to pack the court in the next lame-duck session, Republicans didn't deny it. But voters overwhelmingly rejected the amendment.

In addition, a few years earlier the Legislature had voted to "unpack" the North Carolina Court of Appeals, eliminating three soon-to-be-vacant seats before the state's Democratic governor could fill them. The court would have been left with an even number of judges. A Republican judge resigned in protest, and the Legislature recently repealed the change.

Not every effort to change the judicial system for partisan advantage has originated with Republicans. A bill in the Democrat-controlled Massachusetts Legislature last year would have allowed Democrats to undo high-court appointments by a Republican governor. The bill, which had bipartisan support, would have allowed an elected council with a Democratic majority to decide after seven years whether the Republican governor's appointees would stay in office even if they hadn't reached the mandatory retirement age of 70.

The bill didn't make it out of committee, and the state's Supreme Judicial Court remains composed entirely of Republican appointees.