True, if they don't have an existing law to work from then you have to determine what the law should say. The problem is the current justices have set out to take away people's rights rather than defend them. Like allowing same-sex marriages harms nobody, but conservatives would have you believe they are some how directly harmed by this (your hurt feelings do not constitute actual harm) or that children will somehow be sexually exploited by it (to which they've never been able to show a single case where that was true).

So maybe my earlier statement could be clarified by saying that making laws which intentionally sets people apart, allowing freedoms for one group while taking them away from another group for no reason other than "I don't like something about them" is what is making a mockery of the legal system. I mean I could make the case that conservatives should not be allowed to vote based on their recent history of electing criminals and con men, as this is causing actual harm to the collective nation and to individuals, but that's still just a judgement based on my personal beliefs even when actual physical and monetary harm can be shown, because such a law would still be taking away the rights of one group while still providing the same rights to another group that can have the same problems (even though those incidents are greatly reduced).