PARIS (Reuters) - An adviser to France"s top administrative court favoured telecoms firm Orange ORAN.PA on Monday in a long-lasting $2.2 billion tax dispute over writedowns it booked after acquiring a company in the mid-2000s. A favourable ruling for Orange would compel France’s tax administration to pay the company at least 1.9 billion euros ($2.24 billion) in back taxes it had perceived in 2013. The litigation stems from the integration in 2005 of Orange’s subsidiary Cogecom. This integration led the state-controlled telecoms group to book heavy losses which it offset against profits, thus reducing the basis on which taxes were calculated. The Council of State, France’s highest administrative court, is due to put an end to the judicial saga with a ruling in three weeks. “(Today’s hearing) provided an opportunity to hear the conclusions of the public rapporteur. They are essentially favourable to Orange,” Orange said in a statement. The “public rapporteur” is a member of the Council of State who acts as an adviser to the court. The court is not bound by such opinions but follows its adviser’s lead in most cases.