In practice, something which is against the law is also beyond the law. If I'm honest, I don't normally hear "beyond the law", but perhaps expressions like "beyond what the law permits".
The contexts could be different. For example, stealing money is against the law. There is no acceptable level of stealing. It is simply illegal.
However, the speed limit on most urban roads in the UK is 30mph. Driving is legal, but 40mph is beyond what the law permits, or beyond/over the legal limit.