Also Switzerland has its own national international private law, the IPLA (Federal Act of 18 December 1987 on International Private Law). This contains specific provisions on intellectual property rights. Important for copyright are Art. 110 IPLA and Art. 116 et seq., especially Art. 122 IPLA.
Similarly, Article 110 IPLA leads to the application of Swiss law where protected works are used within Switzerland. However Swiss law is not applicable if the protected work is used abroad.
Article 116 et seq. ILPA are applicable, if contracts with international aspects have been concluded (e.g. foreign contractual party, contractual service has to be performed abroad). In this case the co-contracting parties may determine the applicable law (so-called choice of law; for assignments of copyrights by contract Art. 122 IPLA).
In the absence of any such stipulation regulations are provided in Art. 116 et. seq. For contracts in the copyright domain this will be specifically settled in Art. 122.2 ILPA. In the absence of a choice of law Art. 122.1 stipulates the application of the law of the country of residence of the person granting the intellectual property rights (more in section 1.4).