§1. If there are just causes, the competent major superior, after having heard the council, can exclude a member from making a subsequent profession when the period of temporary profession has been completed.
§2. Physical or psychic illness, even contracted after profession, which in the judgment of experts renders the member mentioned in §1 unsuited to lead the life of the institute constitutes a cause for not admitting the member to renew profession or to make perpetual profession, unless the illness had been contracted through the negligence of the institute or through work performed in the institute.
§3. If, however, a religious becomes insane during the period of temporary vows, even though unable to make a new profession, the religious cannot be dismissed from the institute.
Source: Code of Canon Law (Vatican.va)