The Freeport Doctrine stipulated that

Apopular sovereignty superseded the Kansas-Nebraska Act
Bthe Dred Scott decision voided the notion of popular sovereignty
Cslavery could be prevented by states passing laws unfriendly toward

the practice

Dthe Kansas-Nebraska Act was unconstitutional under the Dred Scott

decision

Ethe Fugitive Slave Act was unconstitutional in territories gained from

Mexico