On 23 October 2023, the Lower Administrative Court (Tribunal administratif) handed down a judgement in direct tax matters, in which it dismissed as inadmissible an appeal lodged with it, on the grounds that the principle of a single lawyer or representative had been breached. The appeal was indeed lodged with the Lower Administrative Court on behalf of the taxpayer by both a chartered accountant and a foreign lawyer practising in Luxembourg under his original title.
While the single-lawyer principle already existed before the judicial courts, it is was for the first time (to the best of our knowledge) that this principle was applied by the administrative courts.
Subsequently, acting this time through one single lawyer, the taxpayer appealed against the first instance judgement arguing notably that the sanction for breaching the principle of a single lawyer or representative could not be the inadmissibility of the appeal in the absence of any effective prejudice to the rights of defence of the State party.
In a judgment dated 7 March 2024 (docket no. 49770C), the Higher Administrative Court (Cour administrative) firstly enshrined the principle of one single lawyer/representative in tax litigation. Secondly, the Higher Administrative Court overruled the decision of the Lower Administrative Court in that the sanction of a violation of said principle may only be an inadmissibility of the appeal lodged with it in case the right of the defence have been effectively prejudiced, which the State party was unable to demonstrate in the case at hand.