[routing-wg]Question about IP block Misusage

Hello, I have a question. I am searhing now what happens if an ISP use IP address space that is assigned to another ISP. Is there any technical control eleminate this condition? And what is the legal sanction of this misuse? This might be intentional or unintentional. But ISP that use another ISP's IP address space damage the Internet nature. Thank you for your answer in advance Best regards, Ali Dinçkan