If you are the victim of a car accident caused by a drunken driver, it matters little what the profession of that person is.
Of course, a police officer should set an example, but so should magistrates, doctors, bankers and so on.
And sentencing someone for a deed based upon their profession, would let, say, a street sweeper get off lightly. This would not only be discriminatory, but only solve a tiny part of the problem, even if certain professionals would never drink and drive again.
Just make booze less generally available; e.g. not at every street corner.