2. What Amendment does the Court base its decision on?

A unanimous United States Supreme Court said that state courts are required under the 14th Amendment to provide counsel in criminal cases to represent defendants who are unable to afford to pay their attorneys, guaranteeing the Sixth Amendment's similar federal guarantees.

can you explain it better

in an absolute  monarchy, the  monarchrules as an autocrat, with absolutepower  over the state and government — for example, the right to rule by decree, promulgate laws, and impose punishments. the  monarch isnominally sovereign but the electorate, through their legislature, exercise political sovereignty.