There is no hypocrsy if we go back to your claim earlier.
If a judge was to say that he once drove his car when young without a licence, does need to step down when judging a case of a driving without a licence case when it comes to court and his attention.
Grove and Cameron have admitted trying substances, they can if it was tried and then realised that they cannot do this ever when put in a position of trust, then of course they can enforce laws that deal with this stuff, but, if they are breaching the trust by taking coke and puff whilst in office and knowing tha actions of this then its hypocritical of them to do so and pass laws.