I READ with interest the recent coverage of the experience of 81-year-old Charlie O'Malley, who was refused a bottle of brandy by an Asda checkout assistant in the Loanhead store, on the basis that his 16-year-old granddaughter was with him at the time.

He had left the checkout to collect a forgotten item, leaving the 16-year-old to pack, who was then asked for ID as the bottle was scanned with her grandfather absent. Mr O'Malley returned and the store manager called for but the sale was refused despite protestations.

Whilst this incident will have been embarrassing and inconvenient for Mr O'Malley, the refusal is not actually as absurd when one considers the ramifications surrounding under-age and agency sales (sales to an adult who means to supply it to under-18s). Too often the media is filled with stories about "rogue licensees" who are painted as putting profit before their obligations as a responsible licensee. Yet when those obligations are fulfilled, the operator also appears to face a backlash.

In my view the store management was entirely correct to support the checkout assistant's decision to refuse the sale. Once the decision to refuse has been made, it should not, regardless of explanation, be overturned because the Licensing (Scotland) Act 2005 provides for considerable penalties should an under-age or agency sale occur. The checkout assistant, premises manager and premises licence holder can all be prosecuted – and the management/owners can be convicted even if they were not physically present due to the doctrine of vicarious liability.

In addition to this, if an under-age or agency sale occurs, the police can ask the licensing board to review the premises' licence and the personal licences of any staff involved. The licensing board, in turn, can suspend or even revoke these licences, meaning a potential loss of livelihood and employment. I have been involved in cases where even simple human error has resulted in licence suspension and convictions.

Licensed premises staff are trained to rigidly stick to the rules on under-age sales. This includes the new condition requiring the "Challenge 25" rule to be observed in shops, supermarkets, pubs and clubs. If the manager performed a u-turn and allowed Mr O'Malley to walk away with his brandy, he would have potentially breached a condition of the store licence, and potentially committed a criminal offence. It is perfectly acceptable that staff be overly cautious. These are responsible operators who are merely being diligent and following the law because if they do not their job, and reputation, is on the line.

The Challenge 25 condition became law back in October 2011 but rather bizarrely, whilst it requires licence holders to have a policy, it does not require that policy to be in writing. Licence holders who have taken steps to introduce "due diligence" by having established written policies on which staff are trained continuously must surely be commended. At the same time, there should be a recognition that a mistake can occur – we are all human after all. The alternative is a fixed penalty system which pays no heed to the circumstances of the event, and lumps all licensees together by treating the responsible ones in the same way as those few "rogues" who play fast and loose with the law. Calls by alcohol health charities for immediate and punitive sanctions when a single "test purchase" failure occurs risk positioning themselves as entrenched and intolerant.

Oe the one hand then, the licensed trade is pilloried for a single error whilst ignoring the wider efforts being made with staff training and responsible retailing policies; and on the other it is lambasted for being overly cautious and being rigid in its application of meeting the terms of its licence.

Embarrassment and inconvenience to the customer is the collateral we must all live with in accepting that there should be strict rules on the sale of alcohol to under 18s.

Stephen McGowan is head of licensing at law firm TLT.