A friend of mine who is a last year international PhD student in the US got his monthly stipend terminated by his advisor. He still has GTF and is working for as a RA for the last three years. During that time, he has published several papers and his research results also brought in money via grant for his advisor. However, he got stuck in a project recently and could not get it done properly, thus after a few bad individual meetings, his advisor threatened to cut his stipend due to bad performance and he actually did. Although he still have two other ongoing and working project and close to graduation, his advisor still admanat about not paying him. He still need to work in the lab in order to graduate. Can professor has right to terminate stipend for student like that? What can PhD students do to protect themself in this situation?