Taking the witness stand in his trial on mail and wire and tax-evasion, Street told a federal jury about his intense study of the history of the federal income tax, the tax statutes and relevant Supreme Court decisions and has come to the conclusion that the tax is unconstitutional.

"If you find it, look it up for me and I'll plead guilty to all these charges," an animated Street told Assistant U.S. Attorney Jennifer Arbittier Williams.

Williams persisted in trying to elicit from Street the fact that he earned more than $2 million in consulting fees from 2000 to 2004 and paid no taxes on it, and that he failed to even file tax returns for three years.

"Street kept filibustering the prosecutor with his legislative research into the tax code, finally saying, "Miss, why can't just show me the law so I can plead guilty?"

"Let's take five minutes," interrupted U.S. District Judge Legrome D. Davis. Then, outside the jury's presence, Davis quietly but firmly instructed the grinning Street, 68, about answering questions in court and the fact that his comments about pleading guilty were "not fair" to a jury hearing evidence in a trial that he wanted.

Earlier in the morning federal prosecutors ended the government's case against former state legislator T. Milton Street, opening the door for the beginning of the defense case.

After Street and his witnesses are done, defense attorney Guy Sciolla will present the case for Street's co-defendant John H. Velardi Sr.

The indictment against Street alleges that he failed to pay taxes on $2 million worth of consulting fees and income not derived from his $30,000-a-year food-vending business between 2000 and 2004, and failed to even file a tax return in 2002, 2003 and 2004.

In addition to the tax charges against him, Street and Velardi, 54, of Media, are charged with wire and mail fraud in an alleged 2003 scheme to defraud a Vietnamese businessman of $80,000 by selling him the rights to a $3.2-million airport maintenance subcontract that Street and Velardi knew did not exist.

Previous witnesses have testified that Street and Velardi wanted to assign the airport subcontract to Thanh Nguyen and his V-Tech Services Inc. to recoup money Street owed Velardi's employer, Philadelphia Airport Services, or PAS, the main maintenance contractor at the airport.

Prosecutors, however, contend that the rights to the subcontract between PAS and Street's Notlim Inc. were no longer Street's to sell.

In June 2003, airport officials had cancelled the Notlim subcontract after Mayor John Street ordered his older brother to withdraw from the deal because it appeared inappropriate. Prosecutors say the ex-mayor was not involved in his brother's alleged crimes.

Nguyen testified Monday that after he paid Street $80,000, the assignment of the subcontract kept getting postponed and Street and Velardi stopped returning his calls.

Prosecutors say that after John Street's election as mayor in 1999, his older brother began hiring himself out as a consultant who could provide an entre to City Hall and city contracts.