Elgalad said:
George Bernard Shaw once said, "Liberty means responsibility. That is why most men dread it."
All of the practices you listed above certainly Do represent liberties. Abortion is the only currently legal one in all the United States, although physician assisted suicide is also legal in Oregon (though that does not cover all of Euthanasia), and Prostitution is legal in Nevada.
Of course, in a federal country, there will always be exceptions.
But it is clear that a society that espouses the ideals of Liberty must also recognize Responsibility as well. Many Libertarians make the case that every behavior that does not impact another citizens rights negatively should be legalized. I used to agree with this stance as well, though I have come to a different realization over the course of my life. Nearly every so called 'victimless' crime actually has many victims.
When you start to name them crimes, you don't give the discussion a fair chance

.
What we should ask ourself is: If certain liberties have victims as a side effect (due to irresponsibility), will we decrease the number of victims when prohibiting those liberties? Or will we decrease the number of victims when we make laws telling under what circumstances these liberties can be enjoyed? And under what circumstances they can
NOT be enjoyed.
That, I believe, is the basic question here!
Drug Abuse affects not only the User, but also their family, friends, neighbors, police, even strangers that they may come into accidental contact one night while racing their car down the street in search of yet another fix. It also impacts health care workers who must deal with overdosing victims, the entire health care insurance industry (because many victims who have reached rock bottom and crashed Have no insurance) and everyone else then who has to pay higher premiums to cover their treatment.
We have laws that allow drug use, drug possesion and drug sales. But these same laws also tell when, where, what drugs and how much. Alltogether, this has simply led to a decrease of the drug problem. Less victims! Less family, neigbours, police and strangers involved!
Prostitution objectifies Women and Children, treating them as nothing more than saleable objects. What future is there for a prostitute who is no longer able to attract customers (assuming they survive that long)? How many diseases, acts of violence, unwanted pregnancies (and abortions), have they had to suffer? In countries where prostitution is legal, there are better conditions for the women, but that does not change the fact that they remain nothing more than commodities to be bought and sold.
It's not nice to put together Women and Chlidren here! Legal Prostitution is about adults!
By legalising prostitution, there will be less diseases, acts of violence, unwanted pregnancies and abortions. Prostitution laws do not only say it is legal, they also specifically say under what circumstances it is legal, and when not! It also leads to a professional labour union for prostitutes.
Whether women choose to be nothing but commodities, is there own business (as long as it indeed is a choice, of course). Apart from that, it would be better not to regard them as nothing but commodities. With the same reasoning, I can argue that a bricklayer is nothing but a labour commodity. Believe it or not, but the average prostitute is just another person, just like you and I.
Gay Marriage seems to be an overlooked freedom for Homosexuals when what it truly represents is a direct assault on the family institution. When homosexuals are offered an alternative equal in every legal aspect other than Name and Religious recognition, they adamantly refuse. Why, if all that they seek are the same protections from the Government that married couples enjoy?
Well, marriage is not just a name, it is a legal thing! It is in your passport, for heaven's sake. You cannot claim it is a religious institution, before it has been banned from any legal document. Not one sane person will step into a private religious institution (aka church) and seek religious recognition for gay marriage! That would indeed be a serious infliction of religious freedom. Such persons should erect their own church, if they want gay mariage to be blessed by a referend.
And, gay marriage is not an assault on family institution. It is a fight for same rights, and possibly a wish to join the familiy institution, not to destruct it!
But of course, abortion on demand and Euthanasia of the old and infirm (voluntarily or not?) are merely representative of personal choice, right? Keep believing that.
Abortion is a discussion we have been over and over and over again here. It is a personal choice of the mother, and, of course, not of the foetus. It is the clash between two rights: the right of the pregnant woman and the right of the foetus. A discusssion whose rights are more valuable, would be annoying now.
On euthanaesia, I'd like to get you out of your dream:
The only way to prevent that euthanaesia will be abused as an excuse to get rid of elderly and infirm people (a valid fear in itself, of course), is when you make a law which exactly describes under what circumstances it can be done. The Dutch law on euthanaesia (first in the world, and possibly still the only one) does not only say it is legal, but also when not. If only people would realise that this law was made to prevent abuse and to decrease murder-like situations....
A hort summary:
Liberal laws do not only legalise things, they also describe when, where, how, howmuch and under what circumstances they are legal. This way, victims of irresponsibility will simply decrease.