Multiple defense tactics are available to Philadelphia District Attorney Seth Williams, say criminal defense lawyers and former prosecutors, but the indictment charging him with bribery and extortion appears formidable if the prosecution's evidence matches the charges.

Federal prosecutors accused Williams of bribery, extortion, and wire fraud on Tuesday in connection with actions that he took as the city's top prosecutor for business figures who lavished him with cash gifts, plane tickets, and junkets to Las Vegas, San Diego, and the Caribbean.

"You have to try to come up with an innocent explanation of the conduct," said Michael T. van der Veen, whose Center City firm specializes in personal injury and criminal defense work.

This was the defense that former U.S. Rep. Chaka Fattah attempted in his public corruption trial, but he was convicted, nonetheless. It has also been unavailing so far for U.S. Sen. Robert Menendez (D., N.J.), who is accused by federal prosecutors of trading official actions for gifts from a Florida physician.

Menendez has sought to overturn the charges, arguing that the gifts came from a friend. And that whatever actions he took on his behalf were merely constituent service, an argument that the U.S. Court of Appeals for the Third Circuit in Philadelphia recently rejected.

Yet State Sen. Larry Farnese, charged in a federal corruption case here, was acquitted in February using similar arguments, van der Veen pointed out.

Prosecutors had accused Farnese of paying tuition costs for a Democratic committeewoman's daughter in exchange for a political endorsement. But the jurors bought defense lawyers' arguments that there was a perfectly innocuous explanation – that the tuition payment was merely a good deed and an act of constituent service.

The indictment draws a tight time line between Williams' receipt of gifts and official acts he took on behalf of business figures seeking his assistance.

Sprinkled throughout the indictment are direct quotes from texts in which Williams asks for financial favors and then confirms that he will take actions to assist his benefactors. In one instance, he agreed to write a letter to help with a businessman's liquor license in California, then under threat from a federal tax conviction. The businessman allegedly gave him cash and a car and paid for trips.

Defense lawyers say they expect Williams' defense lawyers to attack the basic facts of the case wherever possible.

One difficulty Williams faces is that he amended his state and city disclosure forms to reflect receipt of a $45,000 roof, window, and insulation job; Phillies tickets; and a vacation trip to a developer's Florida beach home after a federal criminal investigation already was underway.

One criminal defense lawyer who declined to be identified said the filing will only make it more difficult for Williams to argue that there is an innocent explanation.

The fate of such corruption cases, where intent plays such a critical role, often depends on whose interpretation of the same set of facts prevails, says Peter Vaira, a former U.S. attorney for the Eastern District of Pennsylvania.

"What the defense will probably have to do is glean from the circumstances and statements of the people who gave the gifts what was the intent and what was going on," Vaira said. "The jury could draw the inference that this was improper, or that this was just a dumb thing to do and there's nothing wrong here."

But any defense centered on the notion that Williams was merely receiving an innocent gift from friends could be undermined by charges that Williams took money intended for his mother's nursing home care.

The indictment charges that Williams diverted about $20,000 intended for nursing home payments to his own purposes, spending the money on mortgage payments, tuition and other expenses.

Such a claim of elder financial abuse, if proven, could quickly undermine jurors' willingness to suspend disbelief on the other charges.