In retention elections, voters are asked whether an incumbent should remain in office for another term. The incumbent does not face an opponent and is removed from the position if a majority vote against retention.

State supreme court justices facing retention elections experienced better chances of being re-elected than their incumbent counterparts in other kinds of elections. Since 2008, 155 state supreme court justices have faced retention elections. Incumbent justices won 152 (98%) of these elections. In that same time period, incumbent justices in non-retention elections have faced 196 elections. The incumbent justices won 176 (90%) of these elections. Incumbent justices in all types of election experienced a 93% win rate.

In this time period, Iowa is the only state that has held retention elections in which justices were not retained. Iowa supreme court justices Marsha K. Ternus, Michael J. Streit and David Baker lost their retention elections in 2010. This followed their participation in a decision to remove the state ban on same-sex marriage. The three justices ruled in favor of removing the ban in the 2009 case Varnum v. Brien, resulting in campaigning against their retention by groups opposed to the legalization of same-sex marriage.

Ternus was appointed by Republican Governor Terry Branstad while Baker and Streit were appointed by Democratic governors. They were replaced by Bruce Zager, Thomas Waterman, and Edward Mansfield, all three of whom were appointed by Republican governor Terry Branstad in 2011. Zager’s seat was filled in 2018 by Susan Christensen, who was appointed by Republican Governor Susan Reynolds.