Key legal question
Whether the federal nullity complaint was admissible against the interlocutory decision allowing exculpatory proof.
Extracted holding
The interlocutory ruling on the exculpatory proof was a final determination of a prejudicial federal-law question and was therefore open to nullity complaint.
Extracted reasoning
A decision is reviewable if it finally settles a federal-law issue decisive for the outcome and cannot later be revisited; this was the case for the entitlement to exculpatory proof.