You can, but applying a sudden and severe sanction to conduct that was tolerated for a long time invites an argument under the equal-treatment principle and the good-faith rules of the Labour Law (No. 4857). Where something has been overlooked for months, the employee has reasonably come to treat it as accepted, and that expectation alone can defeat a heavy penalty.
The clean route is forward-looking and consistent. Issue a written reminder that the rule is back in force, state the date from which it applies, and then apply it to everyone without exception; for acts committed after that notice, the graduated disciplinary process can run normally. It matters as well that the earlier tolerance was not confined to particular employees, or you leave the ground open for a discrimination claim. And watch the clock at the other end: a for-cause termination has to follow within six working days of learning of the specific act (Article 26), so past tolerance cannot be used to revive an old incident. Done this way you rebuild the authority and keep the fairness of the process defensible, which is what matters if the file ever becomes a reinstatement or compensation claim.
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