Thank you for your response.
NYC has just passed a law requiring that employer provide sick leave. Further, New York state employment law
states that the employer is bound by the written policies it puts out. It cannot change them at will
after the fact, and in this case your manager does not have discretion to require a doctor's note for one day out, if the policy only requires it after 3 days.
As that is the case, the way you play this is something to consider. If you do not come back with a doctor's note, or tell the manager that you are entitled to not have to have a note, then the manager could end up firing you. Yes, you would have a right to sue for wrongful termination
and would have a right to collect unemployment
, but it would require a lot of hassle.
Knowing that you can enforce your rights in the courts and collect unemployment means that you have recourse should you choose not to get a doctor's note. I can say that personally it is ridiculous for your employer to require a note for a single day off. They are trying to punish you for taking a sick day on a holiday weekend.