From the point of view of the American legal system, what’s the legal status of international government organizations headquartered, or with offices in, the US? Specifically, are they considered to be incorporated entities with corporate personhood? Or do they have some special status as creations of the federal government?
For example, take the Organization of American States (OAS), of which the US is a member. The organization is headquartered in Washington, DC. It maintains an office there, has local employees who are not diplomats, issues publications over which it asserts copyright, etc. Does the OAS need to file papers of incorporation in America in order to do all this? If not, on what legal basis could it sue or be sued for matters relating to these activities? If one of its employees is injured on the job as a result of the OAS’s negligence, does that employee have the ability to sue the OAS in a US court? If the OAS contracts with a company to fix the plumbing in its building, and the work isn’t carried out satisfactorily, can the OAS sue the plumber? On what legal basis can the OAS assert copyright over its publications (since in the US works of the federal government are normally in the public domain)? Does the organization need to file a US tax return? Is it bound by minimum wage, workplace health and safety, and other labour laws?