A discussion of recent threats to judges’ safety, at a bar association conference in suburban Dallas last week, became startlingly specific when Sandra Day O’Connor, the retired Supreme Court justice, recounted that each justice had received in the mail “a wonderful package of home-baked cookies” that contained “enough poison to kill the entire membership of the court.”

The sender, Barbara Joan March of Bridgeport, Conn., pleaded guilty to 14 counts of “mailing injurious articles.” The 14 recipients included the nine justices; the chiefs of staff of the Army, Navy, and Air Force; and the director and deputy director of the Federal Bureau of Investigation. The packages, containing either candy or baked goods, were laced with rat poison.

All mail received at the Supreme Court is screened, and the tainted packages never reached the justices, said Kathleen Arberg, the court’s public information officer. The danger posed by the packages was immediately apparent. Each contained a typewritten letter stating either, “I am going to kill you,” or, “We are going to kill you,” and adding, “This is poisoned.”