Henry Sheffie Geyer (December 9, 1790 – March 5, 1859) was a politician, lawyer, and soldier from Missouri.

Most of Geyer's legal knowledge was gained by working in the office of his maternal uncle, Daniel Sheaffee, who was a prominent lawyer.

[citation needed] He reached the position of pay-master and spent some time stationed at Norfolk, Virginia.

After the war ended, Geyer settled in St. Louis, Missouri, still holding the office of pay-master.

Geyer succeeded Thomas Hart Benton, who ended his senatorial career by insisting that Congress had the power to restrict slavery in the federal territories.

[3] Geyer was elected to the Senate just as his own Whig party was dissolving and prominent leaders took other positions.

[4] During his time in the Senate, Geyer voted for the Kansas-Nebraska bill, which demonstrated his proslavery views.

Geyer was asked to join Johnson because of his knowledge of Missouri law, his experience arguing in front of the Supreme Court, and his strong southern views.

Darnes was indicted for manslaughter for killing Mr. Davis, the publisher of the St. Louis Democratic newspaper, The Argus.

On the eighth day, Dr. Beaumont, a skilled surgeon, performed a trephining procedure on Davis to relieve pressure on the skull.

In his argument, Geyer maintained that Davis' death was caused by the surgery and not the injuries he sustained from Darnes.

Geyer's two day argument was published in pamphlet form, republished in Boston, and used by the New England bar in similar cases.