Key legal question
Whether the public-law appeal was admissible insofar as it alleged violations of federal criminal law rather than a constitutional denial of justice.
Extracted holding
That grievance could only be raised by cassation; as a public-law appeal it was inadmissible.
Extracted reasoning
The appellants relied on federal-law errors in the reasoning, which fall outside public-law appeal and could not be converted into cassation because they chose the wrong remedy despite express notice.