Hugo Black,
Roberts v. United States (320 U.S. 264…
“ Thus Congress conferred upon the courts the power to decide in each case whether to impose a definite term of imprisonment in advance of probation or to defer the imposition of sentence, the alternative to be adopted to depend upon the character and circumstances of the individual offender. All we now hold is that having exercised its discretion by sentencing an offender to a definite term of imprisonment in advance of probation, a court may not later upon revocation of probation set aside that sentence and increase the term of imprisonment. ”
