Q: When I told my manager I had cancer, she was initially supportive and asked a lot of personal questions, which I foolishly answered.

Since then, she's become increasingly critical of my work performance in areas that she used to call "not a problem." Our worst fights occur when she asks me to stay late. In the past I've been willing to work into the evening and to come in on weekends to finish a project, but now I just can't. I need my rest.

She's pointed out that she and everyone work overtime during peak workloads and has pulled out my job application, filled out more than three years ago, in which I wrote "of course" when asked if I was willing to work overtime.

And I'm willing, but just not able. I'm scared I'm going to get fired over this, and won't be able to get a new job because chemotherapy is making me lose my hair and it will be impossible to hide my cancer.

Can she fire me for refusing to work overtime when I have cancer and need my rest?

A: You need an attorney or someone from the Alaska State Human Rights Commission or the Anchorage Equal Rights Commission to look at your job and this situation for a real answer, because it depends on whether overtime is an essential function of your job and whether your supervisor intentionally discriminates against you due to your disability.

The Americans with Disabilities Act protects employees and applicants with cancer if their employers discriminate against them due to their cancer and if the employee can accomplish the essential functions of their job with or without reasonable accommodation. It's possible that a reduced work schedule might be a reasonable accommodation, but that depends on your job and whether overtime is an essential function. Here are four real-life situations where overtime has been found to be an essential function:

When systems engineer Thomas Davis sued Microsoft Corporation, alleging his company should have altered his job duties to accommodate his disability, a hepatitis C infection that prevented him from working more than eight hours a day or 40 hours a week, Microsoft countered that Davis needed to respond to urgent, unpredictable customer problems and regularly worked long days. In that lawsuit, Davis v. Microsoft Corporation, a court ruled that working overtime was an essential function of a systems engineer's job.

In another case, Manigan v. Southwest Ohio Regional Transit Authority, a court ruled that a bus driver needed to be able to drive more than eight hours in a shift and thus the ability to work overtime was an essential job function.

In Davis v. Florida Power & Light Co.¸ a court ruled that the utility needed employees who could work overtime in jobs that involved reconnecting electric power service given the customer need for same-day reconnection, and noted that employees regularly worked overtime and this requirement was noted on the employment application.

In Tardie v. Rehabilitation Hospital of Rhode Island, the court ruled that working more than 40 hours weekly was an essential function for the hospital's director of human resources.

In the four cases listed above, the work done by the employee couldn't easily be shifted to another employee — for example, it would have been hard for another employee to handle the HR director's duties or for a second bus driver to pick up when the first driver completed an eight-hour shift. The fact that your supervisor says "everyone" works overtime during peak workloads and that your company asks for the ability to work overtime on job applications suggests how important overtime is.

If your employer was the one to write me, however, I'd remind them that you've willingly worked overtime for three years and ask them if they could find a way to accommodate you, perhaps by spreading your extra workload among your coworkers. After all, if you've been a good employee, perhaps your supervisor and coworkers can work together to be able to support you during your health crisis.