Under what condition can a security guard refuse service?

A security guard can refuse service when an individual poses a threat to themselves or others because ensuring safety is a primary duty of a security professional. This condition aligns with the guard's responsibility to prevent harm and maintain a secure environment. When an individual exhibits threatening behavior or demonstrates the potential to cause harm, the security guard must take appropriate action to protect all parties involved. This action helps in mitigating potential risks and upholding the safety of the premises they are tasked with securing.

In contrast, while rudeness or disrespectful behavior might be unpleasant, it doesn't inherently pose a physical threat, which is why it may not justify refusing service based on safety concerns. Being busy with another task does not typically provide grounds for refusing service, as proper management of duties allows the guard to address multiple needs concurrently. Additionally, the lack of an appointment may not be a valid reason to refuse service, especially in environments where access is not strictly limited to appointments; flexibility can often be accommodated in such scenarios.