PARENTS of drug-addicted kids learn the hard way that when we think things can’t get worse, they do. As a teenager, my son, Nic, was addicted to methamphetamine, heroin and other drugs. At 20, he had used most of the illicit drugs known to man. But one night, partying with a couple of friends in his basement apartment in Brooklyn, the combination and volume caused him to overdose. One of his friends called 911.

Nic was rushed to the emergency room, where he was resuscitated. When I spoke to a doctor there, I was told that if another 15 minutes had passed before Nic got to the E.R., he wouldn’t have survived. My son has now been sober for five years. I don’t know who called the paramedics, but not a day goes by when I don’t thank him.

Other parents haven’t been so lucky.

So many of the stories I’ve heard, from parents who have read my accounts of Nic’s addiction, begin the same way. He was a wonderful child, a good student. She was popular, a hard worker.

David C. Humes described his son Greg as “Wonderful and bright. A.P. courses, good athlete. Warm. Loving.” On May 19, 2012, “Greg’s earthly story ends,” David told me. His son overdosed and passed out. Someone — David doesn’t know who — dragged Greg outside and placed him in the back seat of his own car. The person then drove Greg to the hospital and left him in the parking lot, where he was found dead.

A few days ago I heard from another father. He told me about his only child, Steve, who overdosed on a combination of OxyContin and Jack Daniel’s. Steve’s friends — “friends” may not be the appropriate word — put him in an ice-filled bathtub, a misguided intervention they had seen on TV. Steve died. His friends didn’t call for help because they were afraid they would be arrested, and they probably would have been.

These children are among many thousands whose lives may have been saved if someone had called for help, and more are dying every day. There’s no reliable data on the number of overdose deaths that could have been prevented had help been summoned immediately. But research suggests that, among those who witness an overdose, the most common reason people don’t call for help is the fear of being arrested.

Meanwhile, the death toll keeps rising. Rates of lethal overdoses — now mostly with prescription opioid pain medications, like OxyContin, and street drugs like heroin — have more than tripled since 1990, leading to over 38,000 deaths in the United States in 2010. Overdose has become the No. 1 nonnatural cause of death in the country.

Responding to this epidemic, 11 states — including North Carolina earlier this month — and the District of Columbia have enacted laws that encourage people to intervene at the scene of a drug overdose. These laws, generally, shield a person who calls 911 from arrest and prosecution for drug use or possession, underage alcohol use and similar crimes. (A few other states offer weaker protections for 911 callers in overdose cases, and many already have so-called “Good Samaritan” laws that protect people from being sued if they are at the scene of a non-drug-related accident and try to help.)

The law that recently took effect in the District of Columbia is among the more comprehensive of the statutes — preventing evidence from being used against a person who called emergency services “if it was found through the process of providing health care.” The law also ensures that a person who calls 911 can’t be arrested, in connection with that call, for a parole violation, and protects people who themselves are OD’ing if they call for help.

Such legislation, of course, won’t touch the problem of addiction; nor will it prevent every death from overdose. But it will save lives.

That message had been lost on Gov. Chris Christie of New Jersey, who “conditionally vetoed” a similar measure last year after it passed the state legislature with bipartisan support, saying it would have let drug dealers “off the hook.”

“How about if the person calling is not a Good Samaritan?” Mr. Christie asked at the time of his veto.

Fortunately, in the months since, Mr. Christie appears to have had a change of heart, thanks to lobbying by parents whose children have died from overdoses. Today, Mr. Christie is expected to announce his support of an “Overdose Prevention Act” that includes a Good Samaritan provision. Should the law pass in New Jersey, that would still leave more than three dozen states without protections for those who call 911 in OD cases.

One state on that list is Pennsylvania, where David Humes’s son died. “If they had this law,” says Mr. Humes, “maybe it would have saved my boy’s life.”

David Sheff is the author, most recently, of “Clean: Overcoming Addiction and Ending America’s Greatest Tragedy.”