Two common but unseen wounds of war — chronic pain and post-traumatic stress disorder — are notoriously difficult to treat. Both can linger long after a return to the homefront, affecting a veteran's ability to successfully readjust to life stateside.

With the deadly risks of frequently used pain relievers called opioids now exposed, it's understandable that many veterans are turning to an alternative — medical marijuana. Despite legality that varies by state, an October 2017 survey by the American Legion found that nearly one in five veterans were "currently using cannabis to treat a medical condition" in lieu of opioids and were reporting better outcomes. It's surprising the number isn't higher given how many aging veterans or those returning from combat suffer from chronic pain — 50 percent and 60 percent, respectively, compared with 30 percent of Americans.

These data from one of the nation's best-known veterans service organizations offer a compelling look at how an old and sometimes demonized drug could ease the suffering of those who have served. But far more rigorous study — meaning research that involves doctor-led trials and rigorously measured outcomes — is necessary before marijuana fully earns its spot in the medication tool box that providers can tap to help wounded warriors.

That's why Congress needs to act without delay in passing a new bipartisan bill championed by Reps. Phil Roe, a Tennessee Republican, and Tim Walz, a Minnesota Democrat who is running for governor. The duo's "VA Medicinal Cannabis Research Act," announced this week, would clarify the authority that the U.S. Department of Veterans Affairs has to research marijuana's role in treating veterans. "When a veteran tells me they're finding relief, I believe them," Walz said in an interview this week.

The bill has the support of the American Legion. And having two influential authors should help speed it through Congress. Roe, a physician, chairs the House Committee on Veterans' Affairs. Walz, a veteran, is the committee's highest-ranking Democrat. Sen. Jon Tester, a Montana Democrat, is expected to champion it in the upper chamber. Tester is the ranking member of the Senate's Committee on Veterans' Affairs.

Still, it's unfortunate that these lawmakers need to draw upon their connections and goodwill to shepherd this through. VA leadership should have embraced the opportunity to research marijuana's potential benefits long ago instead of finding excuses not to do so.

One of these irresponsible foot-dragging episodes came to light late last year in an exchange of letters between Walz and former VA Secretary David Shulkin. Noting growing concerns about opioid risks, Walz and nine other House members called on the agency to wield its world-class research arm to study marijuana's potential to treat veterans. Shulkin's terse and tardy reply in December said federal law restricts the agency's ability to do this — a conclusion a Brookings Institution expert called an "unfortunate combination of false information, incomplete analysis, and incomprehensible logic."

Shulkin was fired in March after a travel expense scandal. It is unclear if President Donald Trump's pick to replace him, Dr. Ronny Jackson, supports VA research on marijuana. But Attorney General Jeff Sessions, whose outdated views on marijuana likely influenced Shulkin's poor decision, will probably still hold considerable sway over the agency's future research direction. Having the Roe-Walz legislation passed or in the pipeline counters Session's antiquated notions. It also sends two strong messages to VA researchers — get going, and Congress has your back. All treatment avenues must be pursued to deliver the care veterans deserve.