A federal appeals court in lower Manhattan had a guest star yesterday — retired US Supreme Court Justice Sandra Day O’Connor.

The first woman appointed to the nation’s highest court sat on the 2nd US Circuit Court of Appeals, where she heard oral arguments in four cases.

“Can I ask you a question? There are four different complaints filed here?” the 82-year-old jurist asked an attorney arguing an employment case. She wore her trademark white cravat over her black robe.

O’Connor — who was appointed by President Ronald Reagan in 1981 — kept a low profile and only spoke once more, to call out, “What?” when she couldn’t hear a fellow judge speak on a Duane Reade fraud case.

Retired justices occasionally hear oral arguments in federal appeals courts.

O’Connor will hear four more cases today, including one involving a lieutenant of mobster John Gotti.