These two passages, written by the Supreme Court within a fifty-year period, represent two differing approaches to the grant of property rights through a so-called rule of capture. The quote from Brenner v. Manson harks back to the one of the most celebrated rule-of-capture cases in property law: Pierson v. Post, which famously held that “pursuit alone vests no property or right in the huntsman.” The quote from Union Oil Co. v. Smith sets forth the alternative practice, which has long been part of the federal law governing the award of property in oil, gas, and other mineral rights. In that branch of property, pursuit alone does confer on the seeker or prospector some rights, known as pedis possessio or “foothold” rights. Such rights are not full property rights – those can be claimed only upon the completion of prospecting claims with a successful discovery of the mineral deposit. They are instead embryonic property rights, good only “for a reasonable time” while the prospector “remains in possession, diligently working towards discovery.”