The conclusive nature of the register confers on the registered proprietor of an interesting Torrens title an ‘indefeasible’ title to that interest. By this term, what is meant is that a title cannot be set aside on the ground of the defect existing in the title before the interest is registered. This principle is the foundation of a Torrens title system. This term is not to be found in the real property legislation enacted in New South Wales. Nevertheless, it is an appropriate description of the nature of the title conferred by a number of key sections of the legislation. Section 42 of the legislation confers its protection on the registered proprietor of any state or interest in land. Proprietor is defined by the act to mean any person seized or possessed of any Freehold or other staple interest in land. Hence, section 42 bestows a title which cannot be defeated not only on the registered holder of the fee simple, but also on the registered holder of any less or derivative interest in the land, such as a mortgagee, chargee, lesse and so on; all are within the term registered proprietor.

Complementing section 42 are sections 45 and 118. Section 45 protects the purchaser or mortgagee for value from being deprived of their registered interest except as expressly provided in the act. Section 45 also prohibits the recovery of land from a registered purchaser or mortgagee for value merely because their land or mortgagor may have been registered through fraud or error, or may have procured the registration of the relevant transfer all mortgage through fraud or error, or may have derived the right to registration through a person who is registered through fraud or error. Section 18 prohibits recovery of land from the person registered as proprietor, except in a number of situations set out in section. This concept of title which cannot be defeated except through the provisions contained in a real property legislation is what is at the heart of the Torrens title system.