Dropping an employee's Spouse & Dependent from Coverage

[MD-Benefits Guy]

I am looking for some input regarding a policy as it relates to the dropping of spousal and/or dependent medical coverage by an employee.

If an employee wishes to drop his/her spouse during open enrollment or any another qualifying event (other than divorce) - as an employer can I legally have a policy that requires proof that the dropped spouse/dependent(s) have coverage elsewhere or that the person being dropped authorizes the drop?

Additionally, if there is a request to drop someone from coverage based a qualifying event - can I have a policy that requires proof of the qualifying event....

My separated spouse just started a new job, so I wish to drop them from coverage.

What is a best practice policy to impose for these circumstances?

Thanks for the input.