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Landmark decision in French market abuse cases

Upon a constitutional motion filed by Aurélien Hamelle, a partner at Allen & Overy Paris, the French Constitutional Council rendered on 18 March 2015 a landmark decision in relation to French market abuse cases.

By virtue of this decision, French law now prohibits duplication of proceedings before the French Financial and Market Authority (AMF), and before the criminal court based on the same facts and against the same defendants.


Allen & Overy presented a constitutional motion on behalf of a client prosecuted for insider trading.

Allen & Overy contended that provisions of the French monetary code (CMF) were unconstitutional because they allowed a new prosecution before a criminal court even when the Sanctions' Commission of the AMF has already rendered a decision on the same facts and in relation to the same defendants.

A landmark decision

The Constitutional Council ruled in favour of our motion and decided that the duplication of proceedings before the AMF and criminal courts is unconstitutional.

The Council recognised that Article 8 of the 1789 Declaration of Human Rights does not prohibit the repetition of administrative and criminal sanctions for the same facts in accordance with different rules and branches of law.

However as:

(a) the administrative offence of insider trading and the criminal offence of insider trading purport to punish the same conduct;

(b) both the administrative and the criminal offences protect the same social interests;

(c) the sanctions imposed by the AMF and by criminal courts for insider trading are of the same nature; and

(d) the decisions rendered by the AMF and by criminal courts can both be appealed before the same Court of Appeal, meaning that both decisions pertain to the same branch of law,

then the CMF provisions are unconstitutional because they fail to prohibit the duplication of AMF and criminal proceedings for the same conduct. The Constitutional Council repealed and quashed the impugned CMF provisions entering into force on 1 September 2016. This means that the French Parliament has until September 2016 to amend these provisions.

The Constitutional Council also ruled that from 18 March 2015 onwards it is prohibited to engage or continue criminal prosecution for conduct on which AMF sanctions' commission has already given a decision against the same defendants. This decision will have a significant impact on the way in which market abuse cases are investigated, and will require closer cooperation between the AMF and the financial prosecution services.

Legal and Regulatory Risk Note