Merryman was arrested for his involvement in the mob in Baltimore, specifically for his leadership in the destruction of telegraph lines, but was not charged, a right normally ensured by the writ of habeas corpus.

The case was taken up by the federal circuit court and its current presiding judge who happened to be Chief Justice Roger B. Taney, a Democratic-leaning Marylander.

Taney believed that the phrase “when in cases of rebellion or invasion the public safety may require it” applied solely to Congress because of its location in Article 1.

Lincoln completely ignored Taney's ruling thereby invoking nonacquiescence, and later asked Congress when they reconvened for a special session on July 4, 1861, “Are all the laws, but one, to go unexecuted, and the government itself go to pieces, lest that one be violated?” [2] Had the destruction of public property been allowed to continue in Maryland, Lincoln would have had to fight an insurrection in the north as well as the seceding states' armies.

However, concerned about further unrest from pro-Southern elements, they voted to keep the railways closed so Union troops could not travel through Maryland on their way to defending Washington, D.C. and other federal enclaves.

[6] While carrying out this policy, Governor Thomas Holliday Hicks allegedly ordered Merryman to aid in the destruction of several bridges north of Baltimore.

Cadwalader's response explained that he was acting under orders from President Lincoln, who had delegated authority to the military to suspend habeas corpus.