US No Surprises Act (42 USC 300gg-111 to 300gg-139) and 45 CFR Part 149 149.420(a)-(b): Do not balance bill for non-emergency services at a participating facility, and never for ancillary services or unforeseen urgent needs

A nonparticipating provider furnishing non-emergency items or services during a visit at a participating health care facility must not bill or hold the patient liable for more than the in-network cost sharing determined under 149.120(c)(1) and (2) unless the notice and consent criteria are satisfied. Notice and consent can never be used for ancillary services: emergency medicine, anesthesiology, pathology, radiology and neonatology items and services whether by physicians or non-physician practitioners; assistant surgeons, hospitalists and intensivists; diagnostic services including radiology and laboratory; and any service for which no participating provider is available at the facility; nor for items or services arising from unforeseen, urgent medical needs at the time of care.