Penal officials in New Jersey, backed by the state legislature, are deciding that the humane way to execute prisoners is by lethal intravenous injection. By killing them with kindness, New Jersey's executioners reject such harsher, unworkmanlike methods as electrocution, hanging, shooting and gassing.

The occasion for this decision was the death sentence imposed in May on a twice- convicted murderer. New Jersey, which had killed 160 men and women in the electric chair before a 10-year execution respite beginning in 1972, restored the death penalty last year. It will become the ninth state to allow injections.

A New York Times story told of an assistant to the governor who recently spent eight months researching the technology of legalized death. He was persuaded to recommend injections after reading a law journal article that detailed the botchings that can occur when, say, a firing squad doesn't aim straight and misses the heart.

Other foul-ups have occurred. In Alabama last April, a malfunctioning electric chair meant that three surges of 1,900 volts of electricity were needed to kill a condemned prisoner. One surge usually does it, except on this occasion, with 34 reporters watching the action, a leather strap holding an electrode on the man's left leg burned away. Fourteen minutes of sparks, smoke and flames--hellfire on death row--passed between the first jolt and the doctor's pronouncement of death.

Without the benefit of a national recall for defective electric chairs, New Jersey officials are demanding efficiency as well as mercy. "Execution technicians" are to be trained. With steady hands that can wield the needle under pressure, they won't be likely to repeat the Alabama thriller.

New Jersey's penologists are seeking to edge away from barbarity. They are really hurtling closer to it. They are not only taking lives but are enshrouding the process in the lie that planned killing can somehow, with the proper laying on of trained hands, be humane. Whether it's a gangland murder by thugs or a death row killing sanctioned by the governor, taking a life coldbloodedly is always an act of horror and terror.

In the history of capital punishment in American prisons, every new technique has been hailed as more humane than the last. Electrocution was said to be better than shooting, which was better than hanging. Then gassing had a vogue.

One of the first politicians to urge death- by-drugs as a humanitarian advance was none other than Ronald Reagan. In 1973, when governor of California, he said: "Being a former farmer and horse raiser, I know what it's like to try to eliminate an injured horse by shooting him. Now you call the veterinarian and the vet gives it a shot and the horse goes to sleep--that's it. I myself have wondered if maybe this isn't part of our problem (with capital punishment), and maybe we should review and see if there aren't even more humane methods now-- the simple shot or tranquilizer."

Reagan's yearning for a simpler way of killing horses and people has proven to be as dotty and unfounded as his yearning for a simpler America. A current suit before the U.S. Court of Appeals in the District of Columbia, brought on behalf of eight prisoners condemned to die in Oklahoma and Texas, raises the question of whether the drugs perform as effectively as they should. Affidavits from anesthesiologists stated that untested and unapproved drugs are used in lethal injections. The suit asks that the Food and Drug Administration hold hearings to gather evidence--if any exists--that the drugs are effective.

The current state of the grisly art suggests the opposite--that the drugs do not induce the "quick and painless" deaths the new humanitarians say they will. Along with defective electric chairs, recalls for drugs may be in order, give or take a few lives.

In New Jersey, it came out that concern for the condemned was not the total story. An assemblyman pushing drugs as the ideal pain-killing killing agent had the comfort of juries also on his mind: "If you're on the jury, the thought of some guy in that chair sizzling is going to bother them. This way, with lethal injections, it might ease their conscience when they come up with a verdict."

Talk of easy death and easy verdicts may extend into the killing chamber itself. The last words from the "execution technician" could be the time-honored ones of medicine, "Just relax, you won't feel a thing."

That lie will be the next-to-last brutality from the state..