[EGreg]

Here is the real question...

Can you program in some code to display on the website “this website owner needs to pay for their site” etc.

and if they don’t pay you, you don’t disable it. And it activates after a while. Plus it would have redundant things so they can’t easily just hire one guy to remove it.

Or it could be some thing that breaks the site in a less obvious way and they call you to fix it.

It doesn’t seem to break any laws that I know of. Do you?

[b_t_s]

I am not a lawyer, and your scenario is getting into the gray zone where you really ought to consult a lawyer to get an even remotely reliable opinion. That said, my understanding is that: You shouldn't get convicted(no crime was committed if you do it right). You might still get arrested(have fun convincing officer donut that you remotely disabled some business's website without hacking). You might get sued in civil court for damages. You may or may not win the civil case depending on the wording of your contract, implementation details of your sabotage, the mood of the judge, and the alignment of the stars. I would still argue that a few hundred bucks to hire a lawyer to send a form letter is safer, easier, and more reliable, assuming of course that the client resides in a country with reasonably strong rule of law. You're trying to use a hacker solution to a lawyer problem, which is both unprofessional and generally frowned on by the legal system.