Final answer:
When a guest is already intoxicated upon arrival at your establishment, you should refuse service and ask them to leave to comply with the responsible service of alcohol regulations and ensure everyone's safety.
Step-by-step explanation:
When a guest arrives at your establishment and they are already intoxicated, the appropriate course of action is to refuse service and ask them to leave. This approach ensures the safety of the individual and complies with many areas' laws and regulations concerning the responsible service of alcohol. The establishment must avoid further contributing to the person's level of intoxication by not serving them more alcohol. Additionally, staff should monitor the situation to ensure the guest does not become a danger to themselves or others and consider options to help them travel safely from the premises, such as calling a taxi or a friend. It is not advisable to serve them alcohol in moderation, provide free non-alcoholic drinks with the intent of continued on-premise consumption, or ignore their level of intoxication.