A defense lawyer at the political corruption trial of Sheldon Silver attempted to show Thursday that the federal government tried to pressure a doctor into explicitly saying he referred patients to Weitz & Luxenberg, where Silver was of counsel, in exchange for $500,000 in state grants for Taub's research.

Defense attorney Steven Molo elicited from Dr. Robert Taub why, despite facing possible criminal charges for lying to investigators, he refused to agree to testify that the Silver referrals were “in exchange for” the research grants.

The “in exchange for” language was removed from a proposed draft of a non-prosecution agreement at the insistence of Taub's lawyer, Lisa Zornberg of Lankler Siffert & Wohl, and that language was not in the final agreement signed by the parties in January 2015 that cemented Taub as the key witness in the criminal case against the former Assembly speaker.