Do US Supreme Court votes have to be unanimous?

No. Sometimes verdicts are unanimous, but more often they are split down political and ideological lines. The Supreme Court has become increasingly polarized in the 20th and 21st Centuries, making unanimous decisions the exception, rather than the rule.

The Supreme Court requires only a simple majority vote to decide a case: If all nine justices are present, five of the nine must agree. The Court must have a quorum of six justices to hear a case.