Story's phrase "unless prohibited by state legislation" was a catalyst for a number of personal liberty laws enacted by Pennsylvania and other Northern states. The laws prohibited state officials from interfering with runaway or fugitive slaves in any capacity. Runaways could not be caught or incarcerated by state action, cases could not be heard in state courts, and no assistance could be offered by state officials to those wishing to recapture slaves. The Fugitive Slave Act still stood, but only federal agents could enforce it. This is known as the "anti-commandeering doctrine."