FORMER GOV. Rendell took to the witness stand the other day in the trial of U.S. Rep. Chaka Fattah to chastise federal prosecutors for criminalizing friendship and normal political activity.

Rendell was testifying on behalf of an old friend, Herbert Vederman, who stands accused of bribing Fattah, who also is close to Vederman personally.

Among the "gifts" federal prosecutors said the wealthy Vederman gave to the congressman was $18,000 for what prosecutors say was a sham sale of a Porsche belonging to Fattah's wife, plus payments to help paid debts owed by his son, Chip Fattah, and to help the Fattah family's au pair pay college tuition.

In exchange (a key phrase), Fattah lobbied on Vederman's behalf with the White House and in Congress to get him named as an ambassador. Vederman never did get an ambassadorship.

In short, the feds say that it was a quid pro quo. Vederman gave the congressman the money so he would lobby for his cause. Vederman's attorneys argue that there was no quid pro quo, only gifts bestowed by an old friend.

Rendell said the charges against Vederman were an overreach by prosecutors, who he said were trying to make Vederman's actions look sinister. The prosecutors, Rendell said, did not understand the political process: "They think everything is done for ulterior motives. They're very cynical."

We won't judge who is right on this matter. We don't have to. A federal jury will decide on the charges lodged against Fattah.

But there are two things to consider here. One is that the money was not made as a campaign contribution, but went personally to Fattah and his family. The other is that Fattah is a public official. So, the question of quid pro quo is relevant.

That said, Rendell's anguish is felt by other politicians. After all, aren't horse-trading and deal-making part of everyday politics? If you are an elected official and make a call on behalf of a large campaign contributor, could that be considered a corrupt act? If a company wanting to do business with the government treats you to an expensive meal, is that illegal? Could you get indicted for intervening in a case involving a political ally?

The public's (and prosecutors') view of these activities often differ widely from politicians'. And many views of what the public considers acceptable have changed

What the public once considered normal behavior - for example, ticket fixing - isn't tolerated today.

If you are a politician who is worried a gift might be seen as a bribe, there is an easy remedy: Don't take any gifts. Under the city's Ethics Code, city employees are forbidden to take any gifts (or gratuities, as they are called). Not even a cup of coffee.

If that sounds ridiculous, then try to draw a line between a harmless gift and the now-defunct practice of contractors pinning a $50 bill to building plans submitted to the Department of Licenses and Inspections and a "tip" to the employees behind the counter to encourage prompt review of the application.

These practices changed because of the corrosive effect they had. People began to feel you needed a political connection or cash to get services.

So, yes, the lines between what is acceptable and what is not have moved - and we're the better for it. Does all this complicate friendships among powerful people, especially when some of those people hold elected office? Maybe, but that's one of the prices you pay if you care about the trust of the people who elected you.