Arlen Specter was the first attorney of record for Ira Einhorn, a leftwing political activist who was obviously and clearly --- from the evidence that was immediately available at the time --- guilty of murdering his girlfriend back in 1977. Through Specter's legal machinations, Einhorn made bail. He promptly jumped bail and spent 25 years as a free man before being held accountable in 2002 for Holly Maddux's murder.
Specter had no ethical compunctions in those days about defending a counter-culture radical. It is pure folly to think he has ever been or is now a principled Republican, or that he's a man who can be trusted to protect Republican nominees to the federal bench or the Supreme Court.