Morally, of course not. Practically, that may be a different matter. Some countries expect policemen - and, indeed, all civil servants - to supplement their meager incomes by taking "baksheesh" (literally, "gracious gifts") from the public, kind of like tipping underpaid waitresses. Such "gifts" aren't considered bribes, but since the size of the baksheesh often determines whether or not the policeman will do his duty, it's hard for Westerners to tell the difference.