BULGARIA - PENAL PROCEDURE CODE
Part two. EVIDENCING
Chapter thirty six. PROCEDURES IN CONNECTION WITH INTERNATIONAL COOPERATION ON PENAL CASES
Section 1 Transfer of Convicted Persons
Art. 456. (4) When under the law of the Republic of Bulgaria the maximum term of imprisonment for the perpetrated crime is shorter than that determined with the sentence, the court shall reduce the imposed punishment to this term. When under the law of the Republic of Bulgaria imprisonment is not stipulated for the perpetrated crime, the court shall determine a punishment corresponding most fully to that imposed with the sentence.
Nullum crimen sine lege
Nulla poena sine lege
EDIT.