Lysander Spooner: Libertarian Hero
The American individualist anarchist Lysander Spooner was one of the last natural law philosophers of the 19th century, and his crowning achievement is arguably the total demolition of the myth of the social contract. Spooner applied a libertarian theory of natural law to the United States Constitution that lead him to reject the authority of the constitution, leading to his radical work "No Treason: Constitution of No Authority", in which he applied common sense standards of justice and contract law to political institutions that delegitimized them. Spooner proved beyond the shadow of a doubt that the state is not genuinely based on consent, that the standard social contract and democratic arguments for the sovereignty of the state is a fraud.
Spooner was also a slavery abolitionist and a strong supporter of the principle of individual secession, which goes hand in hand. While maintaining a radical opposition to slavery, he simultaneously opposed the concept of "the union" and opposed the civil war. He more or less accused the northern states of only reforming and expanding slavery, although he wasn't necessarily completely sympathetic to the confederacy either. Furthermore, he tried to outcompete the government in mail delivery and got shut down by the government. Another notable feature of Spooner is that he explicitly took the position that vices are not crimes, coinciding with the standard libertarian opposition to prohibition laws and authoritarian forms of social planning. While Spooner may have a legalistic aura, his legalism was not statist in nature and he more fundamentally was working with ethics when it comes down to it.
Spooner was loosely associated with the individualist anarchist Benjamin Tucker and the periodical "Liberty". While in the grand scheme of things Spooner's political philosophy was similar to that of other individualist anarchists, it could be said that his approach to property appears to have a distinctively neo-lockean element to it, although Spooner is actually claimed to be a libertarian socialist by some. In either case, some genuine dividing lines did emerge as Benjamin Tucker adopted an egoist position under the influence of the work of Max Stirner, which philosophically clashes with Spooner's natural law position. Spooner was a strong advocate of "natural rights", while a Stirnerite egoism rejects the very concept of "right". So in a certain sense, from that point onward individualist anarchism can be seen as splitting between natural rights proponents and egoists, with Spooner remaining on the natural rights side.
Spooner could be viewed as the first political theorist to take natural law philosophy to the conclusion of anarchism. While Proudhon had of course already come to the conclusion of anarchism, his approach wasn't necessarily a strict natural law philosophy. The earliest natural law philosophies actually justified political absolutism. It wasn't until guys like Locke and Jefferson that it began to meaningfully take a more liberal character, justifying limits on political institutions. But all of these natural law approaches prior to that of Spooner ultimately justified state sovereignty on the grounds of some kind of social contract concept. Spooner took natural law philosophy to its logical conclusion by demonstrating that it is impossible for any state to genuinely be contractual as a state qua state, that all currently existing states must be illegitimate by the standards of natural law. Even Locke invoked the concept of the social contract being undoable, but he didn't take this far enough.
In a sense, Spooner can be seen as merely continueing the Jeffersonian project. The views of some of the later natural law philosophers and classical liberals such as Jefferson and Paine was arguably proto-anarchist in nature. "Philosophical anarchism" was common among the more radical American liberals and heavy emphasis was placed on decentralization. But they always ultimately maintained a pragmatic support for a minimal level of government. Spooner was the first natural law philosopher to overcome this limit, arguably representing the culmination of natural law philosophy. The developement of natural law philosophy in America more or less ends with Spooner, until Murray Rothbard picked it up around a century later and drew heavily on Spooner as a referance.
Spooner has a unique place in the history of anarchism and is worthy of it.