Which supreme court decision granted probationers the right to legal counsel during the revocation hearing?

The probation officer gave hearsay testimony that petitioner had committed the acts of forgery and grand larceny, whereupon the court revoked probation and imposed the maximum sentence of 15 years on the previous second degree burglary conviction. A year later, petitioner filed a habeas corpus petition with the State Supreme Court, claiming a denial of the right to counsel at the combined probation revocation and sentencing proceeding. The court denied the petition.

The preamble of the constitution was written to explain the aim of the constitution