Federal prosecutors and U.S. Chief Justice Judge J. Michael Seabright on Tuesday invoked a 73-year-old tax case against two brothers to link the Kealohas and their co-defendants to a conspiracy that began with the alleged theft of the Kealohas’ mailbox.

The U.S. Supreme Court’s 1946 “Pinkerton Rule” is still taught today at the University of Hawaii’s William S. Richardson School of Law, said Ronette Kawakami, the school’s associate dean for student services, who previously spent 26 years in the state Public Defender’s Office.

“It’s established law,” Kawakami said.

The Pinkerton case involved two brothers who were engaged in tax evasion, Kawakami said.

For the Kealoha case, Kawakami said the Pinkerton Rule means, “If Person B actually steals the mailbox, you, as part of the conspiracy, are also criminally liable for the stealing of the mailbox.”

And, Kawakami said that “with every substantive act committed in furtherance of the conspiracy, you are also criminally liable for that conduct.”

Kawakami never dealt with the Pinkerton Rule during a trial and said, “It’s not easy. It’s a very convoluted kind of legal premise that I don’t think is used very often.”

But “it’s taught in school today,” she said. “It’s solid law.”