Legal experts say the Affordable Care Act’s maintenance-of-effort (MOE) requirement — which prohibits states from tightening Medicaid eligibility — remains vulnerable to legal challenges.

The MOE provision of the Affordable Care Act prevents cash-strapped states from cutting Medicaid coverage — by way of limiting eligibility standards and methodologies — prior to the law’s 2014 expansion. Under the law, the government can withhold federal matching funds from states that don’t comply with the MOE provisions.

Conservative opponents of the law say they could use the same legal arguments to fight MOE standards that they successfully deployed in their Supreme Court argument against the law, the Bureau of National Affairs reports. The Supreme Court ultimately ruled that states do not have to expand their Medicaid programs.

“The amount of money HHS [Department of Health and Human Services] is threatening to withhold if the states don’t maintain the effort is the same amount HHS threatened to withhold if states did not expand their Medicaid programs,” Michael Cannon, director of health policy studies at the Cato Institute, a libertarian public policy research group, told BNA.