The answer to this question is yes in theory – but it’s almost always better not to.
Mostly, people involved in litigation only call witnesses who are willing to give evidence for them. Typically, the lawyer or representative will interview the witness and find out what they have to say, and then draft a witness statement for them that sets out their evidence in a logical order. The witness will then read the draft statement and make sure they are happy with it before it is finalised. That way, everyone knows before the hearing begins what that witness says happened.
If you think someone has relevant evidence to give, but they are not prepared to talk to you or give you a statement, you can ask the tribunal to order them to attend the hearing to answer questions. But what the tribunal can’t do is order them to co-operate with you. So there is a high risk in asking the tribunal to make a witness order against someone who doesn’t want to be there: you don’t know what they are going to say.
Nine times out of ten – probably ninety-nine times out of a hundred – if a witness isn’t prepared to attend voluntarily, you’ll do better not to try call them at all.