Gov. Charlie Baker on Friday afternoon signed legislation closing the books on a landmark criminal justice system overhaul, and offered up a new bill that he hopes will keep the conversation going.

One of the two new laws (H 4012), aimed at tackling recidivism, is the product of a Council of State Governments review and increases access to programming in prisons and jails. The other is a comprehensive package that Baker said "probably has over 100 separate elements that represent a change in the way business is done here in Massachusetts."

"It ranges all the way from the beginning of policing all the way through corrections and all the way back into the runway associated with return to society," Baker said at a press conference, flanked by two dozen lawmakers, Attorney General Maura Healey, former Supreme Judicial Court Chief Justice Roderick Ireland, and Middlesex District Attorney Marian Ryan.

"Viewed as a whole, this bill takes our criminal justice system and makes it better," Baker said.

Among other measures, the bill (S 2371) makes reforms to the bail system, repeals some mandatory minimum sentences for certain drug offenses, requires the creation of new diversion programs and makes some crimes committed by young offenders eligible for expungement.

Baker said there were parts he had "serious concerns" with and would like to see amended. He filed a bill he said would make changes to aspects of the law that need modification and prevent unintended negative consequences.

In his filing letter, Baker wrote that he was submitting new legislation instead of returning lawmakers the bill they'd passed with amendments because that bill contains "urgently needed reforms" and he wanted to "avoid the delay in enactment."

"A number of" the measures Baker proposed are "in the vein of what we view as clarifications, technical fixes," said Sen. Will Brownsberger, who co-chairs the Judiciary Committee.

The new law bans parents from testifying against their children in criminal cases, and Baker is proposing to change that so that parents may testify if they wish to but would not be required to.

He also recommends amending the new medical parole program so that "Those serving life without parole for first degree murder, sexually dangerous persons and sex offenders who have yet to be finally classified will be categorically ineligible," according to the filing letter.

House Speaker Robert DeLeo observed that the governor's bill would go through the regular legislative process.

"The governor has raised some points, and I think that obviously I think it will get a proper hearing, and where we go from there, I don't know," he said.

Baker handed DeLeo -- who called the new law a "turning point for our commonwealth" -- the first pen he used to sign the bill, and distributed the others to Judiciary Committee House Chair Claire Cronin and Brownsberger, Healey, and Rep. Russell Holmes, who he said was "the first guy to start talking to me about this."

Criminal justice reform advocates have been pushing for mandatory minimum repeals and other major changes for years, and Cronin acknowledged there was skepticism that action would come this session.

"Back when we began this process, there was a narrative out there, and I kept hearing it over and over again," said Cronin, an Easton Democrat. "I would meet with people and they would say, 'The CSG bill is not enough and we have to do more,' but they would also say, 'But we don't think you're going to do more.' And as much as the fact that I would explain to people that I started my summer mornings every morning with a cup of coffee and a stack of reading materials on criminal justice, no one seemed to believe us that we were actually going to get this done."

Brownsberger said the new law turned out to do "more than anybody hoped, more than I hoped."

The Belmont Democrat thanked the Republican governor for "choosing to be a voice for change," saying they share the same values and goals. "This isn't one of those 'You're a Democrat jokes," he quipped, to which the governor replied, "I'm not" as the crowd laughed.

One of the Democrats vying to unseat Baker, former Newton Mayor Setti Warren, has said he would have vetoed the bill because of the new mandatory minimum it creates for fentanyl trafficking.

"Drugs like fentanyl are certainly extremely dangerous and I would support increasing the recommended penalties for those who are truly trafficking them, but we have to be smart about this, we have to stand up for our beliefs and we need to recognize that the opioid epidemic is a public health crisis that won't be solved by doubling down on failed strategies in the criminal justice system," Warren said in a statement.

At a press conference earlier in the day, advocates who had pushed for the major reform bill cheered the news Baker would sign it.

Sen. Sonia Chang-Diaz attributed the bill's passage in part to the "relentless persistence" of its supporters.

"We're joyful about this bill, but we're also cognizant about what wasn't in it, and the need to figure out more intentional mechanisms for how we do reinvestment of the savings that are going to accrue to this state over the next several years because of those lowered incarceration rates," she told the News Service. "That's a big deal, so that's what's next."