Gideon V. Wainwright ( 1963)
Clarance Earl Gideon was accused of entering a bar and stealing money in Panama, Florida, so the police arrested him and put him in jail. At his trial, Gideon could not afford a lawyer and asked the judge to assign one. The judge resufed, and had to represent himself in court. Gideon was convicted and sentenced to five years in prision. During his sentence, he studied laws and sent a petition to the supreme court alleging that he had not been assigned a lawyer. In 1963, the supreme court ruled unanimously in favor of gideon.
The amendment to the constitution challenged in this case is the proportion of defense lawyers when the defendant does not have enough money to pay for it. In Gideon case the judge told him that Florida only provided attorneys to indigent defendants charged with crimes that might result in the death penalty if they were found guilty.
The impact that it generated is that the Constitution requieres states to provide defense lawyers for those accused of criminal offenses who commit serious crimes and who can not afford the lawyers themselves.