The event that best describes a cause for the chain of events known as Bleeding Kansas is The Supreme Court ruling in Dred Scott v. Sandford.
This 1857 ruling stated that Congress had no authority to prohibit slavery in the territories, which heightened tensions between pro-slavery and anti-slavery factions. As a result, it contributed to violent conflict in Kansas as settlers rushed to influence the territory's status regarding slavery, leading to the violent confrontations known as "Bleeding Kansas."