The government called its first witness Wednesday in the federal corruption trial of former Assembly Speaker Sheldon Silver. Zack Fink filed the following report.

For federal prosecutors, Sheldon Silver's guilt or innocence may rest on the testimony of a cancer doctor who is at the center of the allegations.

Dr. Robert Taub runs the mesothelioma center out of Columbia University. During testimony, he explained how he and Silver came to work out an arrangement whereby Taub referred patients with cancer to Sheldon Silver who, in addition to serving as Assembly speaker, also worked as "Of Counsel" at a private law firm.

The patients had mesothelioma, a rare cancer often caused by exposure to asbestos. Those cases were also very lucrative, bringing multi-million judgments for Silver's firm, Weitz and Luxenberg, which represented people suffering from mesothelioma. Prosecutors say Silver took the referrals, pocketed the fees, and in exchange, steered two state grants worth $500,000 to Taub's cancer research center.

Taub's testimony largely echoed the government's theory. Taub also claims that Silver told him to keep their arrnagement private.

However, on cross-examination Taub claimed he would never have engaged in a bribery scheme. He also admitted to have initially lied to investigators about his relationship with Silver. He later signed a non-prosecution agreement in exchange for his testimony.

Earlier in the day, Perry Weitz of Weitz and Luxenberg testified that it is common practice for lawyers to receive referral fees. And as for Silver's role as "Of Counsel," Weitz claimed firms hired prominent people all the time to lend prestige.

Leaving court late Wednesday, Silver was asked if he is looking forward to the holidays.

"There is no holiday until this case is over," Silver said. "I'm looking forward to being vindicated."

What's noteworthy about this case is that the defense is not contesting any of the evidence. The entire defense strategy is predicated on the notion that Silver's conduct does not violate the law. Attorneys for Silver are making the argument that all of this is business as usual in Albany, and at the end of the day, there are always conflicts of interests that don't amount to federal crimes.