PHILADELPHIA (CBS) — A Federal judge has set the trial date for Philadelphia District Attorney Seth Williams to begin May 31, a much shorter time than past indicted political figures who’ve recently been tried on corruption charges. So, why is the time frame much shorter?

Federal guidelines order a trial to begin 70 days after a person has been charged — but embattled politicians like Vincent Fumo and Chaka Fattah faced a jury at least nine months after they were indicted.

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David Rudovsky is a professor at University of Pennsylvania Law School and says when setting a trial date, a judge considers several factors.

“There are cases in which judges have made decisions that the case requires a lot more time to prepare.” he said.

In this case, the Judge described the need for a quick resolution, saying it’s best for the public.

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“Is it a legitimate factor that the case involves a public official, here in an elected DA, and that it get resolves quickly?” Rudovsky said. “A judge probably has some discretion to say that it’s a factor, even if it is not a controlling factor.”

Prosecutors have until late next week to turn over evidence they will use in the case. Williams’ lawyers have seven days to review, and could ask for more time.