The letter is the Biden administration’s latest attempt to raise awareness about a 40-year-old federal law that requires almost all emergency rooms — any that receive Medicare dollars — to provide stabilizing treatment for patients in a medical emergency. The Biden administration told emergency room doctors they must perform emergency abortions when necessary to save a pregnant woman’s health, following last week’s Supreme Court ruling that failed to settle a legal dispute over whether state abortion bans override a federal law requiring hospitals to provide stabilizing treatment.