Liability costs are significant for many midwives and can curtail their practice options. Because state law largely dictates limits of liability, coverage costs vary across the country, depending on the content of those laws. For midwives, physician concerns about liability are implicated when state policies or hospital bylaws require that their orders or even their ability to practice require physician countersignature, supervision or collaboration. Studies have shown that concerns over liability motivate defensive medicine, including the use of interventions that carry risks for mothers and babies. Efforts to reform liability policies have largely focused on limiting the "pain and suffering" damages that can be assessed.