The bill amends Chapter 27-18.9 of the General Laws, known as the "Benefit Determination and Utilization Review Act," by adding a new section titled "Medically necessary treatment -- Justification for denial." This new provision establishes that any healthcare service or procedure authorized by a provider for a patient is presumed to be medically necessary. It places the responsibility on insurance companies to provide justification for any denial of such healthcare services or procedures. The bill is set to take effect immediately upon passage.