Shapiro is appearing in an ad, urging voters to retain Justices Kevin Dougherty, Christine Donohue and David Wecht.
All are running unopposed.
It's just a yes-or-no vote whether to extend their terms another 10 years.
Shapiro says they will protect a woman's access to abortion and birth control.
If two of the justices are voted out, Democrats could eventually lose their 5-2 majority on the state's high court.