If there is a patent that exists in the USA on a machine for example, is there any legal implication of using a similar variant of that machine in the UK? If the patent only exists in the US, then what is stopping it being coppied and patented accross europe? Surely this would prevent the patent in the USA from spreading accross europe? its a bit hypothetical, but i have been debating it with a colleague and we cannot agree. What are your thoughts?