the patent claims are construed prior to determining infringement. User rights International treaties such as NAFTA and TRIPs allow member states to create exceptions from the exclusive rights enjoyed by patent owners where the exceptions: do not unreasonably conflict with the normal exploitation of a patent; do not unreasonably prejudice the legitimate interests of the patent owner; and take into consideration the legitimate interests of other parties. Under the Canadian Patent Act, legitimate user rights include prior use, experiments and research, and private non-commercial uses. Further user rights are available under the common law doctrine of exhaustion. Academics submit that user rights may extend to education. Prior uses Section 56(1) of the Canadian Patent Act covers the situation where a person has made or used an invention prior to a patent claim by another person. This would usually occur where the first person did not patent the invention or process and attempted to keep it a trade secret. Canadian patent law protects these good faith acquirers and independent inventors to a certain extent; if the patented invention is an object, then the good faith user can keep using it or sell that particular object without liability. Moreover, where a patent covers an apparatus and a method of using it, the acquisition of the apparatus before the relevant date entitles the owner to continue to practise the method with that apparatus after the patent is issued. However, it is uncertain at present whether section 56 would apply to a patented method or process per se used prior to the relevant date. If the patented invention is a machine or process, then the good faith user may keep selling its output. However, the law after NAFTA favours patent applicants over prior good faith users, and the user may not expand his use by making and selling more of the patented product, build another machine to increase his output, or expand his or her process. In Britain, prior use rights are more extensive. A good faith user's right begins when he has made serious preparations to do the act that would lead to patent infringement, and he may begin or continue to do the act regardless of the grant of patent. If the good faith user's act or preparations to do the act were done in the course of business, then the right may also be exercised by his business partners and transferred