Gov. Mark Dayton on Tuesday signed a bill that sets statewide standards for footage gathered by body cameras on police officers, a controversial measure that pitted law enforcement against civil libertarians and some community activists.

Dayton had previously expressed concern about the body camera bill, and he gave only a terse explanation of support in a letter accompanying word of his signature. "I have signed this bill to honor my promise to legislative sponsors that I would do so, if an objectionable provision were removed."

That provision, sought by law enforcement groups, would have allowed officers involved in disputed events to review such footage before they give an official statement. With Dayton's signature, agencies still gain tight control over the recordings of officers in their interactions with the public.

Under the new statewide regulations, members of the public will only be able to view body camera footage if it shows an officer discharging a weapon or causing someone substantial bodily harm. Footage is otherwise considered private, but individuals recorded by a body camera can obtain the data on their own, and nothing bars them from releasing it.

Critics have said the new regulations undermine one of the major intended purposes of body cameras in the first place, to hold police officers more accountable.

Dayton signed 19 other bills into law, including an effort to crack down on opioid abuse with a new requirement that prescribers and pharmacists must register and maintain user accounts of opioid prescription history.

The online registry is designed to identify patients who are abusing drugs, particularly prescription opioids, by obtaining excessive prescriptions from multiple prescribers. The monitoring is in response to a tenfold increase in deaths over the past two decades from the abuse and misuse of prescription opioids such as oxycodone.

"I don't want another family to have to experience loss related to opioid abuse," said Rep. Dave Baker, R-Willmar, a champion of the legislation whose son died from an opioid overdose.

Separately, Dayton vetoed a 51-page bill that made a host of changes to public pension plans in the Minnesota State Retirement System and Teachers Retirement Association. In his veto letter, Dayton noted that the bill reduced cost-of-living adjustments for retirees by .25 percent in the general plan and 1 percent for teachers.

Dayton wrote that he believed the pensions bill should demand similar adjustments of employers and current employees — not just retirees. "It is not fair, and I cannot agree to it," Dayton wrote.

Lawmakers have argued that an aging Minnesota populace requires them to find ways to address rising pension costs. But Dayton said lawmakers should revisit the issue in 2017 and take a more wide-ranging approach.

Also Tuesday, Dayton line-item vetoed $8.4 million in spending on natural resources projects that originated with the Legislative-Citizen Commission on Minnesota Resources. The group is charged with distributing Minnesota Lottery proceeds to environmental resources.

Dayton said he didn't take issue with the specific recipients of the dollars but rather objected that House Republicans shorted a number of other projects recommended by the group's citizen board.

"This action seriously undermines the integrity of a process that includes citizens who volunteer hundreds of hours each year reviewing and recommending projects for funding," Dayton wrote.

Rep. Tom Hackbarth, the GOP sponsor of the bill, said Dayton took down projects that were widely supported and in some cases sought by agencies that are part of his administration.

Dayton did not take action Tuesday on the two biggest remaining pieces of legislation: about $300 million in new spending and another $260 million in targeted tax relief. Dayton is also expected to speak this week on the prospects for a special legislative session, which many lawmakers want in order to finish a construction bonding bill that collapsed in the final minutes of the regular session.

Star Tribune staff writer Jeremy Olson contributed to this story.