I'm curious about the legal consequences of freely distributed software (e.g. open source). I wonder if the author/provider could be held liable if they: - knowingly (passively) or actively market to US customers (e.g. provide support) - are aware that US users are using it, and take no actions to prevent its distribution etc.

Can someone share their knowledge on this?

If European software incidentally infringes a US patent, and it is distributed freely, is the provider then liable? E.g. is Github basically liable for restricting US users from access to (distributing) patent infringing software?