Extradition and European Arrest Warrant ACT
Chapter two - CONDITIONS FOR EXTRADITION. GROUNDS FOR REFUSAL OF EXTRADITION
Article 8 - Extradition may be refused:
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3. Where in the Republic of Bulgaria criminal proceedings against the person whose extradition is requested are pending in respect of the offence for which extradition has been requested;
Admissibility challenge
Admissibility challenge - State investigation or prosecution
EDIT.