After an infamous Supreme Court opinion which claimed that the Federal Fugitive Slave Act precluded a Pennsylvania state law that prohibited blacks from being taken out of Pennsylvania into slavery, the state of Massachusetts passed a personal liberty law on May 21, 1855.
This law made it illegal for any state or local government official to aid in the capture of a fugitive slave. It also denied the use of state jails to be used in the housing of captured runaways, and granted them the right to habeas corpus as well. These and other provisions contained in the bill curtailed enforcement of the Fugitive Slave Laws because of federal reliance on state support to enforce the act.
The act appears to have been quite effective, too. There is no record of a person being taken back to slavery from Massachusetts under the federal act after passage of the state law.
Understanding these provisions can be usual in resisting federal power on various issues today.