The president of the Competition Appeal Tribunal (CAT), Mr Justice Marcus Smith, has been reprimanded for serious misconduct after handing a love letter to a junior staff member.

Details of the reprimand – the most serious sanction short of removal from office – were published by the Judicial Conduct Investigations Office (JCIO) on 8 August.

A senior nominated judge, who investigated the complaint, said Smith “had abused his position and crossed lines which should not be crossed” causing distress to the member of staff that was “likely to be lasting”.

The investigation was launched by the JCIO in May after it received a complaint about the letter in which Smith referred to the challenges of his role and “also stated that he loved the member of staff and wanted to know if this was reciprocated”, according to the JCIO’s disciplinary statement.

The complaint was “accompanied by a summary document which described a series of prior events, for example the judge sharing information about his relationship with his judicial leadership and asking the member of staff to go for walks with him”.

The JCIO statement said Smith had acknowledged the letter was “plainly inappropriate” and had “caused significant emotional distress”.

“On reflection, he realised that he had been ignoring warning signs about his workload and health,” the statement said. “He had come to realise that the letter was a poorly framed attempt to reach out for support and to discuss his problems.”

Smith assured the JCIO he would not repeat the behaviour and would be “taking immediate steps to address the underlying issues which he believed had led him to act as he did”.

In its summary of the nominated judge’s findings, the statement said: “By writing and giving the letter to the member of staff, he [Smith] was clearly expressing his love for her and that he wanted to take things further. His actions were part of a course of escalating conduct towards a junior member of staff who was in a very vulnerable position in relation to him."

The judge also noted that Smith “had shown little insight into why his actions were so wrong” and “had not acknowledged the romantic aspects of the letter, focussing instead on his own circumstances and feelings”.