Laws are the results of decisions by politicians, so they are inherently political. But we also have a website law stackexchange.
How do I tell if my question belongs on Politics.SE or Law.SE?
Law stackexchange is good for questions about what the legal situation in a specific situation is. Politics stackexchange, on the other hand, is about political processes which result in laws.
So when you want to know "according to law X, is it illegal to do Y?", your question should be posted on law.SE. When you want to know "What were the arguments to enact law X, who backed it and who opposed it?" your question belongs to politics.SE.
An exception from the above rule can be a case where a law directly affects political process. For example "Does the Elbonian law allow parliament members to accept presents from lobbyists?" might be a question which would also work on Politics.SE.
But this is a fringe-case. Such question might be on-topic on either website. Use your own judgment about which website will likely give you a more useful answer.
Let's say there is currently a heated political discussion in your country about tighter regulation of chinchilla ownership. You want to form an opinion on the issue. That means you might be interested in which laws already affect chinchilla owners. But that alone does not make the question on-topic on Politics.SE. If it would, any law would be on-topic, because any law can be subject of political discourse. In fact almost any aspect of daily life can be subject of political discourse. But we can not be experts for any aspect of life.
So whenever you want to know more background information about the issues politics meddle with, you will get a better answer on a more specialized SE site. In this case you would ask law.SE about what laws apply to chinchilla ownership, on pets.SE if the proposed laws could actually improve the well-being of chinchillas and on health.SE how harmful chinchilla bites are for humans.