The Swiss Parliament passed a new law in March 2023 that requires federal government agencies to publish all government software under an open source license. The new "Federal Law on the Use of Electronic Means for the Fulfillment of Official Tasks" (EMBAG, Article 9 "Open Source Software" https://www.fedlex.admin.ch/eli/fga/2023/787/de) went into effect on January 1, 2024. It is the result of 12 years of lobbying by the Swiss Parliamentary Group for Digital Sustainability to ensure that the law not only allows governments to publish open source code, but actually makes it the default process (https://www.ti8m.com/en/blog/open-source-gesetz-schweiz). The presentation will outline the history of the legislative process and present the current open source activities of Swiss government agencies, also in the context of the ongoing political debate on digital sovereignty (https://www.inside-it.ch/lasst-uns-die-digitale-souveraenitaet-nicht-verschlafen). The subsequent discussion will focus on what the Swiss government should do next to successfully implement the law. Suggestions such as establishing an Open Source Programme Office (OSPO) like the EU and launching a national Open Source development platform like OpenCoDE in Germany are on the table. More input is needed since Switzerland lacks a strong open source culture compared to other European countries.