After working on your paper for a while, you will most likely discover aspects you didn't initially think of. You should therefore be open to revising your research topic.
It is quite possible that differences in legislation do not affect the biological criminal evidence when investigating environmental crimes. If this is the case, you should consider looking at a different type of crime. Perhaps you need to change your interrogative or rewrite your topic.
Try rewriting this research topic:
Different legislation in Norway and the USA - what are the consequences for the police's opportunities to use biological evidence when investigating environmental crimes?
Remember to give a brief account of the primary elements of the legislation, as well as an account of how these differ. You will need to select the elements you consider most relevant if the paper becomes too extensive.