Legal Question in Technology Law in California

Web sites don't practice illegal activity, any more than telephones do. The illegal activity is being practiced by persons (human or corporate) who own or have access to the Web site.

If the illegality is important enough, or bothersome to you, you can try to determine which police entity or district attorney would have jurisdiction over the persons who are conducting the illegal activity. Sometimes this is quite difficult to determine. Then make as full and complete a report as possible.

I'd also point out that law-enforcement agencies are busy with serious crime and tend to do a "triage" on new complaints, acting on those that have a threshhold likelihood of arrest and conviction in comparison with the seriousness of the threat to the public.