Whether you can be fired for substance abuse depends on various factors, including the laws and regulations in your country or state, your employment contract, and your employer's policies.
In many places, employers have the right to establish policies regarding substance abuse in the workplace. They may require employees to follow drug-free workplace policies and undergo drug testing. If an employee violates these policies and tests positive for illegal substances or abuses drugs or alcohol, the employer might have grounds for disciplinary action, including termination.
However, it's essential to consider the context and any potential legal protections. In some jurisdictions, employees with substance abuse issues may be protected under disability laws if the addiction qualifies as a disability. In such cases, employers may have to provide reasonable accommodations, such as offering help through Employee Assistance Programs (EAPs) or giving time off for rehabilitation.
To fully understand your rights and the specific laws and regulations in your area, it's essential to consult with an employment lawyer or human resources professional who can provide guidance based on the current legal framework.