A 1950 law makes it illegal to picket or parade "in or near a building housing a court of the United States, or in or near a building or residence occupied or used by such judge, juror, witness, or court officer" with "the intent of ... obstructing justice or .. influencing any judge, juror, witness, or court officer ..."
Republicans seem pretty sure this should apply to pro-choice demonstrators near the homes of Supreme Court Justices. So far they have not complained about pro-life and pro-choice demonstrations near the Supreme Court.
Historical context shows the law was intended to be about criminal cases, not policy issues. Applying it to the latter might violate the 1st Amendment.