Drug use is kept private and employers have a right to know about it in some cases. What do you think? Do you agree with me or no?

Question

"Drug use is kept private and employers have a right to know about it in some cases."
I'm not sure I understand what you're saying here. I would agree that employers have a right to know what their employees are doing on the employer's premises. In other cases they probably have the right to know what their employees are doing regardless of where they are. Most professional sports have a zero tolerance policy for drug use. Some other professions have such policies too.
I'm not sure what to agree or disagree with.