The of the subject must be reasonable considering the factors of physical surroundings, physical contact, and the type and level of any threats.

The Detention  of the subject must be reasonable considering the factors of physical surroundings, physical contact, and the type and level of any threats.

Explanation:

Shop keeper's Privilege and the Merchant Privilege:As per the doctrine of the common law the shopkeeper or the merchant can detain and question a person if they have a doubt on the person that they have committed an illegal act.

The detention by the shopkeeper is considered proper if:

The detention is not a physical restrain,it may have arised out of the words ,conduct,behavior of the the person.If the reason or the cause for detaining a person is reasonable.The person who is detained has committed some crimeReasonableness:The Detention  of the subject must be reasonable considering the factors of physical surroundings, physical contact, and the type and level of any threats.Consistency: The policy of the Retailers should be same or equally applicable irrespective of the race or personal characteristics of the individual

The answer is an appellate court.