Are there laws against such kind of discussions?
In general, someone who provides advice to further the commission of a crime, or prevent its prosecution, can be charged with "aiding and abetting," or as an "accessory" or "conspirator." So anything that could be construed as participation in or solicitation of an actual crime is not allowed here.
Note that a lawyer can't advise a client to break the law, and in various circumstances a lawyer has professional and official responsibilities to notify authorities of intended crimes.
Fortunately, not only does Law.SE not provide legal advice, but also requests for legal advice are considered off-topic.
Even in the U.S. it is possible to run afoul of the law by communicating certain information. A request for illegal information would certainly be off-topic.
So what's left? At least in the U.S., it is not generally forbidden to discuss the elements of a crime and how the law enforcement system works and might be frustrated in finding and proving them. So, for example, the classic, "I'm writing a book and a character commits crime X. Could he get away with it by doing Y?" is not a priori off topic. Or, for example, "Could A have gotten away with murder if he had just done Z?"