The grieving mother accomplished what would have been inconceivable a few short years ago, much less back when the nation launched its war on drugs: She helped pass a bill, signed by a Republican governor, that lets people get away with using drugs for the sake of saving lives.

The state’s new “Good Samaritan law,’’ which immunizes from prosecution people who call 911 to report an overdose even if they are using drugs themselves, is part of an emerging shift in the country’s approach to illegal drugs.

Four decades after the federal government declared war on narcotics, the prevailing tough-on-drugs mentality is giving way to a more nuanced view, one that emphasizes treatment and health nearly as much as courtrooms and law enforcement, according to addiction specialists and other experts.

The changes are both rhetorical and substantive, reflecting fiscal problems caused in part by prisons bulging with drug offenders and a shifting social ethos that views some drug use as less harmful than in the past. States are driving the trend.