Thomas Jefferson borrowed directly from English philosopher John Locke when he wrote that people possess "unalienable Rights" to "Life, Liberty and the pursuit of Happiness" in the 1776 Declaration of Independence. Locke's 1689 "Two Treatises of Civil Government" argued that every person is born with rights to life, liberty, and property -- rights that exist before any government and that no king or legislature grants. Jefferson swapped "property" for "the pursuit of Happiness," but the framework stayed the same: these rights come from human nature itself, not from a constitution or a court.
This idea drove the American Revolution. If rights come from nature rather than from King George III, then the king cannot legitimately take them away -- and colonists have grounds to revolt when he tries. The concept also shaped the Bill of Rights, which does not "grant" freedoms like speech or assembly but instead prohibits the government from violating freedoms that already exist. Today, debates over natural rights surface whenever courts consider whether a right is "fundamental." The Supreme Court has used natural rights reasoning in cases from gun ownership (District of Columbia v. Heller, 2008) to marriage equality (Obergefell v. Hodges, 2015), asking whether a right is deeply rooted enough in human experience to deserve constitutional protection.