In the 1915 Supreme Court case Frank Guinn and J. J. Beal v. United States, Chief Justice Edward White held that the grandfather clause, an amendment to Oklahoma’s constitution, limited black suffrage and was therefore invalid. The case also applied to Maryland’s constitution, which had a similar clause. The grandfather clause worked in conjunction with a literacy test to deprive African Americans of the right to vote. The literacy test stipulated that all voters be able to read, but the grandfather clause lifted literacy test requirements for anyone who was otherwise qualified to vote anywhere in the United States on January 1, 1866. The clause was particularly galling to African Americans in Oklahoma, as that state had not even existed in 1866. The literacy test additionally discriminated against African Americans, since it was very subjective and was applied by white southern registrars.