According to TITLE 77: PUBLIC HEALTH CHAPTER I, 250.1110,
"For any nurse who does not agree to employment requiring on-call hours, the refusal of a nurse employee to agree to such on-call availability shall not constitute grounds for retaliation, discrimination, dismissal, discharge, or any other penalty, threat of reports for discipline, or employment decisions adverse to the nurse employee."
"The hospital may defeat the claim of a violation by presenting clear and convincing evidence that an unforeseen emergent circumstance, which required overtime work, existed at the time the employee was required or compelled to work."
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I suggest you try to negotiate a solution without resolution to the courts. Litigating this matter will be expensive and very emotionally draining.