These include slurring and dishevelment and any two of those could see someone turned away.
Breath tests were not used as part of that assessment.
"It was only provided as an option to the patron if they dispute our assessment," he said.
"It's only used for resolving disputes. We actually don't use it to assess intoxication, we look for visible signs of intoxication.
"There's no specific limit, it's simply a tool for us to show the patron that our assessment is correct."
Mr Harmon said seven breath tests were performed yesterday and seven people were not allowed into the ground because they were assessed as under the influence, out of a crowd of about 14,000.
Others were turned away for trying to smuggle in alcohol, while some spectators were evicted for their behaviour inside.
Sometimes, security staff might tell fans to go away and drink some water and eat before they head back to the stadium.
Mr Harmon said other stadiums and events, such as the league Nines, also used breath-testing, and it was in the sevens' alcohol-management plan.
From Mr Churchman's party of 20, 18 were allowed in.
Mr Harmon said there was very little alcohol-related trouble yesterday, a far cry from two years ago when there were 156 breaches of alcohol rules.
This resulted in cancellation of the liquor licence and sevens organisers having to apply for a special one each year.
Mr Harmon said the atmosphere in the stadium was good, the family zone full and he was taking his own daughters to the sevens this afternoon, something he wouldn't have done in the past.
He said yesterday one person was treated by ambulance staff for intoxication. Three years ago, 20 people were treated.
The sevens' reputation as New Zealand's biggest party led to it becoming a focal point for cracking down on drunken behaviour and it was difficult for stadiums and venues with thousands of people, Mr Harmon said.
But he acknowledged it had to change.
"It's very difficult for stadiums to comply with the act and it's very important for us to show police and liquor licensing authorities that we don't have intoxicated people on the premises."
Mr Churchman said the definition of being drunk in public needed to be clarified, because those not allowed into the stadium were able to enter bars for lunch.
He questioned what right a security guard had to breathalyse him when he wasn't in a car.
When he raised that, Mr Churchman said the security guard's response was the stadium was private property and managers could test whoever they wanted.