Over the next 12 months an estimated 8,000 Americans will die in agony. They will be suffering the almost unbearable pain of terminal cancer. Congress has the power to relieve this pain, but effective action will require a measure of political courage -- and political courage is a commodity always in short supply on Capitol Hill.

What is proposed is that Congress authorize physicians to prescribe heroin for hospital patients "for relief of intractable pain due to terminal cancer." The Senate bill sponsored by Hawaii's Daniel Inouye contains carefully drawn safeguards. The heroin made available to hospital pharmacies would be manufactured under government license. The drug could be prescribed only by doctors registered under the Controlled Substanes Act, and it could be given only to patients having cancer "with a high and predictable mortality."

Behind Inouye's bill is a 10-year campaign led by the National Committee on the Treatment of Intractable Pain. These are some of the arguments that support the committee's efforts:

Heroin is the most effective painkiller ever discovered. The drug first was synthesized in England in 1874. The Bayer Co. of Germany began marketing it in 1898, and for the next quarter-century heroin was widely prescribed as an analgesic. Lamentably, the drug was so widely and so loosely prescribed that many users became addicted. In 1924 Congress prohibited the manufacture and importation of heroin, but hospitals were permitted to keep their supplies for emergency use. In 1956 even that privilege was revoked. Heroin has not been legally available in the United States since 1960.

Meanwhile, other nations, notably England, have continued to make heroin available to ease the pain of cancer victims. The drug acts more quickly than morphine; it causes less nausea and vomiting; administered by injection, heroin is 21/2 times more potent than morphine, and because of this characteristic much smaller doses are required.

No other analgesic has the unique properties of heroin. Physicians recently have been experimenting with a drug known as Dilaudid-HP, marketed by Knoll Pharmaceuticals. It is better than morphine (it is more soluble and more potent), but according to an article in the New England Journal of Medicine, the new drug has more side effects and less painkilling action than heroin.

Last year, Rep. Henry Waxman (D- Calif.) sponsored a House bill along the lines of Inouye's bill. It was a good bill, and it had impressive bipartisan sponsorship. But on Sept. 19, with elections only seven weeks away, the bill died under an avalanche of "no" votes. The count was 355-55 against it.

How could so humane a measure be rejected so roundly? Some members feared that if hospital pharmacies were stocked with even small amounts of heroin, the pharmacies would become more vulnerable to robbery. Others feared that the hospitals' supplies somehow would be diverted to street sales. The main reason the bill failed was that many members, seeing that the measure would be defeated, were unwilling to cast votes that might be interpreted back home as "pro-heroin."

If committees in both chambers will act promptly, perhaps the bill will pass this time. As Waxman told the House last year, only 2 percent of all drug-related robberies occur in hospitals. Their pharmacies already carry stocks of other controlled substances, and there is little reason to believe that the relatively minute stocks of heroin would enlarge the risk. As for diversion, Waxman made the point that the whole nationwide program probably would not require more than 15 pounds of heroin -- this, compared to the tons of heroin illegally available through the underworld commerce in narcotics.

To suggest that those who support the bill are "soft on drugs" is absurd. Not one line in the Inouye bill implies the slightest relaxation in the government's tough line against dealers in controlled substances. His co-sponsors include such liberal Democrats as Riegle of Michigan and such conservative Republicans as Warner of Virginia and Symms of Idaho. Their sole aim is to relieve the terrible pain of persons dying of cancer by permitting physicians to use the best means toward that end. The bill ought to pass without a dissenting vote.