It still doesn't set precedent. In Australia, they are separate areas of law.
Also, if you want to argue the slippery slope, then it starts at allowing marriage full stop. By logic, your argument that a man and woman can get married sets precedent for any other type of marriage.
Then saying that means that all law is then liable for being abolished and we would live in utter chaos...
Human nature is to push the boundaries and once someone else gets it changed then 'hey I might as well push my case too' because that is the mentality.
If I'm wrong then I'll shut up but just wait and see...
I feel like Noah right now. The rain is coming people!!!
You still don't get it. They are separate arguments. If the time comes to debate, say polygamy, then so be it, but it gets debated on it's own merits.