Final answer:
If an intoxicated guest drives away despite your efforts to provide alternate transportation, call law enforcement immediately with the person's vehicle details and direction of travel, and consider contacting someone at their destination. Document your prevention efforts for legal purposes.
Step-by-step explanation:
If your efforts to provide alternate transportation for an intoxicated guest are unsuccessful and they drive away, you should take immediate action. The first step is to call the local law enforcement and provide them with all the necessary information, including the intoxicated person's vehicle details and the direction in which they were heading. This is crucial as it is a matter of public safety and it may help prevent a potential accident. Secondly, if you know the individual's destination, you may consider contacting someone at that location to warn them. Documentation of your efforts to prevent the individual from driving can also be important in case there are legal implications later on.