BOSTON (AP) — Massachusetts must temporarily suspend one of its key restrictions on Zohydro, a powerful new prescription painkiller, pending the outcome of a lawsuit challenging their constitutionality, a federal judge ruled on Tuesday.

U.S. District Court Judge Rya Zobel ordered the state to stop requiring doctors and other prescribers to issue a so-called “letter of medical necessity” stating that “other pain management treatments have failed” before prescribing the hydrocodone-based drug.