In a rare bipartisan effort, Congress approved sprawling legislation — the Opioid Crisis Response Act of 2018 — designed to make it easier for states to expand access to addiction treatment. Addiction treatment advocates say two provisions — one that would allow Medicaid, the federal-state health insurance plan for the poor, to pay for residential treatment in large facilities and another that would allow Medicare, the federal health plan for people 65 and older, to pay for methadone treatment — will substantially improve access to treatment.The legislation, approved last month by the House and Wednesday by the Senate, also would pay for research into opioid alternatives, support greater use of non-opioid pain management and invest in new law enforcement efforts to curb illicit drugs.Some critics say the legislation, which calls for roughly $8 billion in federal investment over five years, doesn’t go far enough given the magnitude of the drug overdose crisis.