A stunned store owner was visited by police after asking a shopper, who didn't have a mask on, to leave.
Kevin Brown, who manages The Original VG store in Middlesborough, requested that the customer either put on a face covering or provide proof he was medically exempt.
However, when he did neither, he was asked to leave.
Nearly a month later, Mr Brown had two Cleveland Police officers turn up at his shop over allegations he had "discriminated" against the man and been verbally abusive towards him, Teesside Live reports.
Mr Brown, who has worked at the convenience store for 37 years, said: "This guy came in without the mask on. I asked to put a face covering on, and he said I'm exempt. I said he needed to show proof or he wasn't coming in.
"He said 'I don't need to show you ID, and that it is against the law for you to ask' - he said I was discriminating against him."
Claiming the man had "no visible disability", he added: "I never once asked what was wrong with him as that's nothing to do with me.
"But if I don't then anyone can just walk in, say they are exempt - and then what can I do about that?"
According to the Government, it appears his options are limited.
While face coverings are mandatory for those who aren't exempt, The Department of Health and Social Care told Teesside Live that business owners are not responsible for enforcing the rules.
It has left Mr Brown questioning just what powers he has to protect his business, his staff - and himself.
"I'm just trying to protect everyone else as well as the customers, so you don't know if you're doing right or wrong - it is a headache.
No action was ultimately taken following the clash, with Cleveland Police stating the complainant - who they say were disabled - opted not to take it to court.
A force spokesperson claimed the man had "felt discriminated against due to his disabilities and exemption from wearing a mask", while the reason he didn't wear a lanyard was out of "fear of being targeted in the local area".
However the saga has left Mr Brown seething. Since the start of the covid pandemic, he's enforced a "very strict" mask policy at the Lealholm Crescent shop, in Park End, which has posters plastered all over urging customers to cover up.
With covid having caused him major staffing absence issues - never mind claiming over 150,000 British lives - he's understandably keen to keep the virus out.
As such, in his mind, he felt he was doing the right thing in challenging the man for not masking up - and felt the law was on his side.
However he's now hit out over the lack of clarity as to just what powers actually are available to business owners who dare to challenge someone for not covering up.
"When (the police) turned up I just thought that this is the final straw," he added.
"I mean, what are we supposed to do if they don't wear a mask?
""I don't know where I stand."
Currently, face coverings are "required by law in most indoor public places" including shops with those who flout the law fined £200.
Yet while the Government's website states transport operators can stop customers from entering a bus or train without a mask, there's no mention of what a shop worker should do - while it adds that exemption cards are a "personal choice" and "not required by law".
When Mr Brown and his staff have challenged customers over not wearing a mask, he claims "nine out of ten" eventually do cover their face.
However, some take it too far, adding: "One guy spat at us about three weeks ago and (customer) were swearing at us just yesterday.
"It is beyond a joke. Because you are a small staff they think they can come and abuse you, and they look down on you."
Teesside Live approached both Cleveland Police and the Department of Health and Social Care (DHSC) for clarity over what traders can do if someone refuses to wear a mask.
The Government department didn't comment directly. However it pointed out that, by law, customers must wear coverings unless exempt - and staff must too, when they are in an area where they are likely to come into contact with the public.
Shop owners must also notify customers of the law - like Mr Brown has with his signs. However, again, they pointed out they aren't responsible for enforcing it.
According to GOV.UK, that would be up to the police, as well as PSCOs, who "can enforce compliance if members of the public do not comply with this law without a reasonable excuse."
Yet as he points out, people pop in his shop for a couple of minutes to buy the essentials. If he was to ring the police, it isn't realistic to expect to hear sirens approaching by the time they leave the store.
As for Friday's police visit, Mr Brown said he had no issues with the two officers who he accepts were just following up a report.
However he's questioned why he feels he was made to feel like a suspect for upholding a law - which he sees being openly flouted every single day.
He added: "I just can't get my head around what we are supposed to be doing in that situation,
Addressing the incident at the shop, a Cleveland Police spokesperson added: "The reporting person says that he entered the shop at around 6pm on 18 December and was shouted at by a shop assistant for not wearing a mask, he explained he was exempt and the male shop owner asked for proof of exemption, which the reporting person said they did not have to provide and they didn’t wear a sunflower lanyard for fear of being targeted whilst in the local area.
"The reporting person then says they were verbally abused by the staff and the customers in the shop at the time and were forced to leave.
"A report was then made to us of a disability hate crime. Officers investigated the report and spoke at length to the reporting person and to the staff in the shop this week.
"The matter has now been closed as the reporting person did not wish to progress a criminal prosecution to court."
