Translate the following English sentence to French:
"It is, after all, only the most serious crimes which would have consequences under criminal law. Ninety per cent of cases would be disciplinary matters concerning negligence or incompetence."
Seules les affaires les plus graves feraient l'objet de sanctions pénales ; 90 % des affaires seraient de nature disciplinaire et concerneraient de la négligence ou de l'incompétence.