Judgment of Bulgarian Supreme Court (Върховен съд) No. 508, Civil Case No. 817/95 of June 6, 1995

Rationes Decidendi:

Jurisdiction is a procedural conditio sine qua non; it is considered to be a prejudicial (preliminary) question.
The jurisdiction of courts in civil cases can be excluded by an arbitration agreement pursuant to Section 9(3) of the CPC. The existence of such an arbitration agreement constitutes a procedural obstacle, which prevents the court from ruling on any substantive issues, including such issues on which the court would otherwise be obliged to rule (sua sponte).
A conflict of jurisdiction between a court and another authority shall be assessed by the court sua sponte at any point during the proceedings.
An arbitral tribunal is not another authority. A lack of jurisdiction of a court due to the existence of an arbitration agreement is therefore considered by the court exclusively upon request, which must be submitted by the end of the fi rst hearing in the case. If the jurisdictional challenge is not raised by the stipulated deadline, the objection is precluded.