Freedom of association includes both the positive right to association as well as the negative right to refuse to associate with others. It is acknowledged in international law that no one may be compelled to belong to an association.
Regional instruments have explicitly recognized the right not to associate. According to Article 10 of the African Charter
Similarly, the IACtHR has noted that
The 2011 Venice Commission opinion on the rights of non-registered associations in Belarus describes the principle as follows:
However, a clear distinction has been made between the right not to join an association and compulsory membership in a public association. The ECtHR has held that compulsory membership is not an interference with Article 11 provided that it is done by a public association that pursues aims in the general interest, such as public control over the practice of medicine, and in doing so acts as a kind of public authority (see Association Section 1.3).
The ECtHR examines on a case-by-case basis the “public” nature of the organization imposing compulsory membership.  The classification in national law is only the starting point. In a case involving compulsory membership in the Icelandic taxi association Frami, the ECtHR found a violation of the freedom not to associate where the public interest role of the association could have been served through other means than compulsory membership:
The IACtHR has also provided grounds for determining whether compulsory membership violates the freedom not to associate, for example, when it infringes on other rights, such as freedom of expression. At the request of the government of Costa Rica, the IACtHR issued an advisory opinion on compulsory membership in an association prescribed by law for the practice of journalism. The specific request concerned “whether there is a conflict or contradiction between the compulsory membership in a professional association as a necessary requirement to practice journalism in general, and reporting, in particular.” The IACtHR found that the law in question – which would have required to journalists to be members of a “colegio” (association) in order to practice journalism, limited membership only to those who had completed a particular university specialization and imposed criminal penalties on those who failed to comply – constituted a violation of the right to freedom of expression [Article 13 of the ACHR] in that it denied such persons access to the media as a means to express themselves. The Court distinguished journalism from other professions in that
While the IACtHR in its majority advisory opinion primarily focused on the right to freedom of expression, Judge Rafael Nieto-Navia issued a separate opinion stating that requiring journalists to join the association in order to practice their profession infringed on their right not to associate. The judge’s argument mirrored the logic of the ECtHR that there is a difference between journalist associations and those that “fulfill strictly public aims which transcend private interests.”