To sum up, in theory you can find a lot of solutions to this problem, but in practice, actually some people who hunt without permission aren't punished.

in 是介词，在这里表示"在...方面"或"按照...来说"。 theory 是名词，来自希腊语 theoria（观察、思考），指"理论、学说"，与"实践"相对。 in theory 这个短语表示"从理论上说"或"按道理讲"，强调某种观点或结论是基于理论推导而非实际经验。