How/why is that?

Let's say that the legal entity is registered in Switzerland or China or Russia for that matter.

This company sells some goods [virtual/physical] through a web site [for example using Amazon 1-Click patent] to a person, who happens to be an American citizen, with payment made by credit card.

How this company will become "subject to these rules and ridiculous software patents"? In which court will this case be processed? How the court decision will be enforced?