Glad that the author is raised this thread without referring to an individual case. To answer this question, we need to know the responsibilities of celebrities first. Celebrities are people who have reached a particular status in the eyes of the public wherein their actions, their thought process, their conduct is imitated or liked by their fans and admirers.
The public figure has a huge responsibility of being a good role model, a good citizen and to have a good sense of right and wrong. For instance, a celebrity promoting an event that is inappropriate for the society, against national integrity etc. High on the list is breaking the law or committing a crime.
There are so many avoid paying tax and bending the rules, we don't bother much but the same when a celebrity fails to paying due taxes, it becomes a headline and sets a bad precedence (avoiding duty on imported cars etc). There are people with unregistered or with country made weapons but the same takes an entirely different path when a public figure does it. The fans and followers would automatically think that it's ok because his or her celebrity has done it.
So, I feel the celebrities should be held accountable within the legal framework and an exemplary punishment would send out a strong message for both sides, 1. if this is the punishment for a powerful celebrity, the fate of a common person committing the same crime would be inescapable, 2. for the new celebrities, it would be a deterrent to avoid getting carried away with their status and thoughts that they can escape the law of the land.