As Hawaii gets close to opening its first medical marijuana dispensaries — some 16 years after medical cannabis was legalized — one might expect that the major issues have been worked out.

Not so. Even as the state Department of Health labors under a fast-approaching April 15 deadline to approve eight applications for dispensary permits, the Legislature is busy, too — trying to change the rules under which the Health Department is working.

It’s the legislative equivalent of trying to change the tires on a car while it’s speeding down the freeway — in other words, a bad idea.

There are dozens of bills related to marijuana in the Legislature this session. Some of the provisions in those bills would loosen the requirements imposed by last year’s Act 241, as implemented by the Health Department through its administrative rules.

House Bill 2707, for example, would allow not just doctors, but advance practice registered nurses to certify patients for medical marijuana. It would allow cannabis samples to be transported interisland for testing. It would create a 15-member Medical Marijuana Advisory Commission that would report annually to the Legislature on how the program is working. It would authorize the use of paraphernalia like vape pens and pipes. It would allow dispensaries to sell marijuana cigarettes, which the DOH has opposed on health grounds.

Senate Bill 2523 would override DOH rules by allowing marijuana to be grown in greenhouses, shade houses and open-air growing centers, rather than in enclosed indoor facilities that would require powerful grow lamps.

There’s nothing wrong with improving on the medical marijuana law, and some of these changes make sense. Registered nurses already authorized to prescribe prescription drugs should be allowed to do the same for prescription medical marijuana. Also, greenhouses and similar setups can be a reasonable alternative to indoor facilities, given Hawaii’s fair climate and high electricity costs — as long as the bill is strengthened to adequately specify the minimum security standards to guard against theft.

Even so, the dispensing of medical marijuana in Hawaii represents a major change in the state’s health landscape. The Health Department’s rules may prove overly cautious and in need of reform. But the department is obliged to place the health and safety of Hawaii’s citizens over the promotion of the medical marijuana business. To change the rules even before they’ve been tested would be unwise.

There is good reason for a cautious approach. A 2013 Justice Department memo, cited in SB 2707, noted that states are expected to strictly control the cultivation and distribution of legal marijuana “to prevent diversion of marijuana outside of the regulated system.” Failure to do so could result in the federal government challenging “the regulatory structure itself.”

Changing the law also raises the question of whether those who applied for dispensary licenses would gain an unfair advantage, as the deadline to apply has closed. Some potential applicants may not have applied because they were unable or unwilling to follow the current, stricter rules.

The integrity of the dispensary selection process has already been tested by the Health Department’s resistance to identifying those who will choose the permittees. Thankfully, the department was pressured into changing its mind. Now it should be allowed to get the dispensaries online as planned without further complications or, more important, without further delays.