 By insisting therefore that positive law is subject to this substantive constraint, Locke subjected the legislature to a discipline of uncertainty. Because the natural right of property was controversial, so the administration of any substantive constraint along these lines was bound to be controversial. And because the substantive constraint was supposed to affect the validity of positive law (Locke 1689: §135), the effect would be that some people—let’s say those who disagreed with Locke about the claims of labor over occupancy—would disagree with him about which positive rules of property are valid and which are not. 