The McPherson v. Blacker case in 1892 involved a dispute over the method of selecting electors for the Electoral College in Michigan. The state had passed a law allowing each congressional district to choose its own elector, with two at-large electors chosen statewide - a departure from the previous system where all were selected on a statewide basis. A group of voters challenged this law, arguing that it violated both Michigan's constitution and the U.S Constitution by not ensuring equal representation. However, the Supreme Court ruled against them, upholding Michigan's right to determine its own process for choosing electoral college members as long as it did not violate any specific prohibitions laid out in either constitution. The court stated that there was no constitutional requirement for states to use popular vote or ensure proportional representation when selecting their presidential electors; instead they could use whatever method they saw fit.

In the dissenting opinion for McPherson v. Blacker, Justice John Marshall Harlan argued that Michigan's law allowing its legislature to determine how electoral votes were allocated was unconstitutional. He believed that the Constitution’s language about states appointing electors "in such manner as the Legislature thereof may direct" referred only to setting qualifications and procedures for choosing electors, not deciding which candidate they would vote for in advance. Harlan contended this interpretation violated citizens' right to equal protection under the Fourteenth Amendment by effectively disenfranchising voters who did not support the majority party in their district or state. Furthermore, he asserted it undermined federalism principles because it allowed individual states too much power over national elections.