‘Any economic operator may be excluded from participation in a contract where that economic operator:
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has been convicted by a judgment having the force of res judicata in accordance with the legal provisions of the country of any offence concerning his professional conduct;
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has been guilty of grave professional misconduct proven by any means which the contracting authorities can demonstrate;
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Member States shall specify, in accordance with their national law and having regard for Community law, the implementing conditions for this paragraph.’