American political philosopher and 19th-century activist Lysander Spooner wrote a great deal about social justice and individual rights. In addition to harming those who were directly enslaved, he thought that slavery was inherently wrong because it went against natural law, which holds that human rights are inalienable and exist outside the purview of the state.

Spooner opposed the notion that the enslavement of one generation could somehow excuse or legitimize the enslavement of another. This viewpoint is comparable to asserting that breaking a vase in your house does not grant you the right to break other vases in your community. On its own, breaking a vase is wrong, as is every instance of slavery in Spooner's case.

He believed that the system of slavery was an ongoing injustice in which every enslaved person suffered regardless of whether their ancestors were also slaves, rather than merely a historical transgression. According to Spooner, regardless of historical injustices that may have impacted earlier generations, each person's rights and dignity should be upheld.

By highlighting this issue, Spooner pushed society to view slavery—and consequently all forms of oppression—as an ongoing transgression of natural law rather than a problem that is fixed with the liberation of successive generations. His writings continue to have an impact on conversations about justice and human rights because they challenge people to consider the moral ramifications of decisions that have an impact on people in various contexts and eras.