The 68-year-old former Manhattan Supreme Court official was riding with her husband Nathan, a criminal defense lawyer, when the accident happened shortly after noon Saturday in the Chelsea neighborhood of New York, the New York Daily News reported.
"She stopped at a light and I went on ahead," Nathan Dershowitz said. "A block later I stopped and turned around, and I saw the lights from the police cars."
The truck kept going after striking her. Police caught up with the driver but said it did not appear he knew he had hit someone.
Marilyn Dershowitz had worked in the court's civil division where she oversaw several high-profile divorce trials, the Daily News said.
Her brother-in-law, Alan Dershowitz, is a Harvard law professor who is frequently called upon for his analysis of national legal issues.