What is a "reasonable" request by a worker to be accompanied at a disciplinary or grievance hearing?

Section 10 of the Employment Relations Act 1999 provides that, if a worker reasonably requests to be accompanied at a disciplinary or grievance hearing, the employer must allow them to be accompanied by a trade union representative or by a fellow worker.

There is no expansion in the Act on when a request might be unreasonable.

The Employment Appeal Tribunal in Toal and another v GB Oils Ltd EAT/0569/13 held that there is no requirement for an employee's choice of a particular companion to be reasonable, provided that the companion is within one of the prescribed categories, ie a trade union representative (within the meaning of s.10(3) of the Employment Relations Act 1999) or another of the employer's workers. Section 10 states only that the request to be accompanied must be reasonable, not that the choice of companion must be reasonable. The Acas code of practice on disciplinary and grievance procedures was amended in March 2015 as a result of this case, as the previous version suggested that a request could be unreasonable due to the employee's choice of companion, for example the choice of a companion from a remote geographical location if someone suitable was available on site.