Several U.S. Supreme Court justices appeared hesitant Monday to block a $6 billion bankruptcy plan for Purdue Pharma, the maker of OxyContin, that includes controversial legal protections for members of the Sackler family who as the company’s owner allegedly helped fuel the opioid crisis.

The U.S. Trustee Program, a part of the Department of Justice and overseer of the bankruptcy system, has challenged the Chapter 11 plan over its release of liability for the Sacklers in exchange for contributing up to $6 billion to victims of the opioid crisis.