You mentioned Copyright, but asked about patents. Copyright laws and patent laws are quite different (and they vary from country to country). Trademarks are covered by yet another body of laws.

One thing is certain. Since people are being persued even when they observe copyright and patent laws, one can definitely be persued when breaking them. It's a question of mitigating risks, a job for a lawyer. Hopefully, you're too small to be worth more than a "Ceast and Desist" request — What's the point of suing someone if you're not going to get anything from it? — but even that could have a major effect on an operation