The term of a patent is 20 years from the filing date of the application (see Article 14 LPI or Article 63 para. 1 EPC). Before expiration of the term of twenty years a patent can expire by renouncement or because of non-payment of annuity fees. After expiration of the patent, the invention may be used by everyone. In the field of pharmaceutical products, supplementary protection certificates are available in many countries, which may prolong the term of protection ( in Switzerland, for example, up to 5 years, cf. Articles 140e LPI).