As per the topic, can a venue legally force a supplier working there (contracted to the event organisers, not the venue itself) to wear a mask regardless of the supplier being exempt?
It depends what you mean by the term “mask”, but if we set aside the more normal Health & Safety requirements for handling certain substances, say, or working in particular environments, in which it would normally be the suppliers responsibility to operate under the relevant standards, we could look at the venue’s organiser’s rights/responsibility. In the context under consideration, it is down to each individual to decide whether to declare themselves ‘exempt’. Exempt is exempt, and non negotiable, in effect. No third party is required.
If they do not allow someone in, they are at risk of being sued for discrimination, either by the individual concerned, or maybe by the supplier itself. What it would cost is highly variable, depending on the financial outcome, you’d have thought, but there have been out-of-court settlements with individual customers denied services etc for this reason, with damages being paid by the culprit. E.g. https://disabilityrights.org.uk/first-face-mask-discrimination-case-nets-7-000 - this one’s a long way back.
