Hi 'blackness'!
First of all, let me say that while all IFLRY's member organizations define themselves as liberal, there are still quite some divergent opinions with regards to (particularly) the issues you bring up.
In general, I think it should first be admitted that these are not exactly the 'victimless' or innocent acts as you state. People on (hard) drugs are much more inclined to commit crimes against other people, which could be one of the reasons for banning (hard) drugs as it increases the level of fear in society. Also, people on drugs run more often into health problems, putting an extra burden on the public health sector in many countries and thus penalizing tax payers. Finally, it is always a difficult moral question how 'free' the drug user actually is when he/she has got addicted...
With regards to prostitution, the enormous amount of trafficking taking place in order to cope with the demand (either legal or not) raises concerns about the rights of those women...
I agree that there are good reasons for the liberalization of particular issues (at least soft drugs legalization), but it is too easy to consider them as only being harmful for the utilizer. Moreover, many of us will believe that certain preventive measures may sometimes be preferable to repressive-only measures...
Any thoughts?
"Bliss was it in that dawn to be alive,
but to be young was very heaven!"
William Wordsworth, 1789