Mike Grennan, a former convict who's getting by piecing together small construction gigs in Port Huron, Michigan, says he's paid his debt to society — but, when it comes to getting an occupational license to be a home-building contractor, he just can't outrun his criminal past.

That's because Michigan, like two dozen other states, has laws on the books that prevent ex-felons like Grennan from getting the professional licenses they need to work in a variety of blue-collar trades, including cutting hair, welding, doing makeup and cosmetics, construction and more.

"It really frustrates me. I have a really good work ethic, and I've paid my debt to society," said Grennan, 46, who has been in and out of state prison for chunks of his adult life, due to a series of convictions he said stem from an addiction to heroin.

Mike Grennan finds work as a subcontractor for small projects in Port Huron, Mich., but he hasn't been able to get his occupational license to be a homebuilder because of his criminal past. Courtesy Mike Grennan

Now, a growing number of states are trying to bring down the barriers convicts face in re-entering the workforce after their release — and that includes a new raft of laws in recent months that have drawn bipartisan support and are aimed at making it easier for ex-cons to get occupational licenses in fields from which they were formerly barred because of their criminal pasts.

Since his 2013 release from Michigan's Jackson State Prison, where he served a three-year sentence on larceny and stolen property charges, Grennan has been blocked from getting his residential maintenance and alteration contractor's license — which he needs to legally work as a homebuilding/renovation contractor. That's because of "good moral character" clauses in Michigan law that essentially prohibit people with felony convictions from getting approved for more than 70 percent of occupational licenses granted by the state.

More than 70 million Americans with prior criminal records are facing similar barriers to re-entering the workforce, where 25 percent of all jobs require an occupational or professional license, according to the National Employment Law Project, a left-leaning workers rights nonprofit based in New York.

"You're looking at crisis in which a large proportion of the American public are just locked out of all sorts of jobs, which not only hurts them and their families, but creates a challenge for employers, often times in in-demand occupations that are looking for qualified workers," said Maurice Emsellem, NELP’s Fair Chance Program director.

The added irony, Emsellem and other experts said, is that so many others, in similar situations to Grennan, actually learned their trade in prison, where they were preparing to come out ready to find a job and re-enter society — only to find out that they can't.

Inmates training to become commercial underwater divers receive classroom instruction at the California Institution for Men state prison in Chino, California. They are among those who can get the licenses they need to get jobs. Patrick T. Fallon / Bloomberg via Getty Images

"There's a lot training happening in construction and manufacturing inside prisons," Emsellem said. "People go through all this effort to reform themselves. And then they can't work when they get out. It's an extraordinary and powerful irony.”

This year, at least eight states have tried to fix the problem.

In March, Delaware Gov. John Carney, a Democrat, signed into law a measure removing some obstacles for former convicts seeking licenses in cosmetology, barbering, electrology, nail technology and aesthetics. Under the law, state licensing boards can no longer include convictions older than 10 years as part of their consideration process; and the waiting period prospective licensees must observe before applying for a waiver of a prior felony conviction was slashed to three years from five.

Weeks earlier, Indiana Gov. Eric Holcomb, a Republican, signed a similar bill that eliminated "good moral character" and "moral turpitude" clauses from licensing board requirements and forced boards to limit disqualifying crimes to those "specifically and directly" related to the profession in which the applicant was seeking a license.

Also that month, Nebraska Gov. Pete Ricketts, a Republican, signed bill mandating that occupational licensing boards render their decisions about whether past convictions would be considered disqualifying before applicants spend time and money on training and classes. Previously, applicants had to complete relevant training before even applying for their license.

Similar laws have gone into effect this year in Tennessee, Wyoming, Kansas, Maryland and Massachusetts. And since 2015 — following a set of best practices for state lawmakers published by the Obama White House regarding occupational licensing reform — at least seven other states have put laws on the books lessening licensing restrictions for applicants with criminal histories, according to the Institute for Justice, a libertarian-leaning public interest law firm.

The restrictions were originally enacted to increase public safety by ensuring that licensed tradespeople met high standards, experts said. But states that have maintained such obstacles to re-entering the workforce for former convicts have actually seen public safety harmed, according to a widely cited 2016 study by Arizona State University economics professor Stephen Slivinski, because the laws result in significantly higher rates of criminal recidivism. The study also found that states with fewer restrictions have lower rates of recidivism.

Even as bipartisan support in state capitals across the U.S. for reform is growing, not everyone's on board.

Bill Cobb, who now works as the deputy director for the ACLU's Campaign for Smart Justice, knows all about it.

In 1993, Cobb, then a 24-year-old college student in Philadelphia and a veteran of Operation Desert Storm, pleaded guilty to robbery, criminal conspiracy and kidnapping charges for driving the getaway car in a crime. After he served a six-year sentence at a Pennsylvania state prison, Cobb enrolled in a Philadelphia program that would set him up to get an occupation license for commercial truck driving.

"I took out thousands of dollar in loans, passed all the written exams," Cobb said, "only to find out that that I would not even be able to get a job driving as a result of not being able to get an occupational license."

Cobb later found work as a telemarketer before embarking on an advocacy career to help people who faced a similar predicament coming out of prison. "I did my time. I was ready to move on and live my life well," he said.

Pennsylvania has to date rejected substantial changes in its licensing laws.