A trustee seeking to litigate on behalf of a trust must establish their authority to do so by producing the trust deed, which demonstrates the legal nature of the trust, its constitution, the identity of trustees, and the powers vested in them. Failure to attach the trust deed is fatal where authority is challenged. Furthermore, an applicant seeking an interdict over property registered in the name of a company must establish at least a prima facie right in its own name to that property or demonstrate its legal interest in the company. Without establishing such a right or interest, the applicant lacks locus standi in judicio to institute proceedings, regardless of allegations of fraud or misrepresentation concerning the company's property.