Why and how did some northern state legislatures reject the federal governments passage of the fugitive slave act?

Some northern state legislatures rejected the Fugitive Slave Act due to strong abolitionist sentiments and the belief in states' rights. They viewed the law as morally objectionable and an infringement on their sovereignty, leading them to pass personal liberty laws that aimed to protect escaped slaves and hinder the enforcement of the federal act. These legislative actions reflected a growing resistance to slavery in the North and a commitment to civil disobedience against federal mandates perceived as unjust.