Clarence Earl Gideon was charged for breaking into a pool hall and steeling some beverages and five dollars in cash.
He did not have enough money to buy a lawyer, so he asked the court to provide him with one and they said "No".
Sense he did not have a lawyer he defended himself in front of the jury.
The jury found him guilty and sent him to five years prison.
When in prison, he petitioned the Supreme Court telling them that they didn't provide him with a lawyer and that that was violating the 6th amendment. They gave him another trial with a lawyer and he proved his client not guilty.
Now a criminal in court has a right to a lawyer and states have to provide them.