landmark • Northern States, 1850s

The Juries That Helped End Slavery

The Fugitive Slave Act made it a federal crime to help escaped slaves. The government brought dozens of prosecutions. Juries in the North refused to convict. Case after case ended in acquittal or hung jury, making the law nearly unenforceable.

Historical illustration of the Underground Railroad and Northern resistance

A Law Designed to Be Airtight

The Fugitive Slave Act made it a federal crime to help escaped slaves. The government brought dozens of prosecutions against abolitionists and ordinary citizens who aided people fleeing bondage. The law was a political compromise designed to preserve the Union by forcing the North to actively participate in the institution of slavery.

Historical illustration of the Underground Railroad network across Northern states — Photo: Ann Ronan Picture Library / Heritage Images / Getty Images

“Northern juries repeatedly acquitted people accused of helping enslaved people escape. They made the most powerful nation on earth unable to enforce its own law.”
— Historical account of Fugitive Slave Act resistance

Juries of Conscience

Juries in the North refused to convict. Case after case ended in acquittal or hung jury.

In Syracuse, New York, 24 people were indicted for rescuing William “Jerry” Henry from police custody. Three of the first four trials ended in acquittals. The government dropped charges against everyone else.

In Boston, after two acquittals and several hung juries in the Shadrach Minkins rescue case, the government gave up — even though President Millard Fillmore himself had demanded prosecutions.

Judge the Law as Well as the Facts

One legal historian noted that defense lawyers told juries “that they should judge the law as well as the facts, and that if any of them conscientiously believed that the Fugitive Slave Law was unconstitutional, it was their duty to vote for acquittal.”

Federal judges regularly admonished jurors not to vote their consciences. It didn’t work. The law was unjust, and juries refused to enforce it.

A Law Made Unenforceable

Over time, these repeated acquittals made the Fugitive Slave Act nearly impossible to enforce in the North. Prosecutors couldn’t get convictions. Citizens became emboldened to help. The law, which had been designed to crush anti-slavery sentiment, became a tool of humiliation for the slaveholders and their allies.

Federal prosecutors in Northern states reported extremely low conviction rates for Fugitive Slave Act cases.
Several Northern states passed “personal liberty laws” that made jury trials mandatory for accused fugitives.
The inability to enforce the Act became a key grievance driving the South toward secession.

Ordinary citizens, sitting in jury boxes, said “No. This law is wrong. We will not help enforce it.” They couldn’t change the law directly — but they could refuse to convict. And eventually, the law changed.