The Supreme Court sharpened the bite of laws regulating the scandal-plagued commodity business yesterday when it ruled that victims of fraud or manipulation in that rapidly expanding industry can sue for damages in the federal courts.

The 5-to-4 ruling subjects commodity futures brokers, merchants and even exchanges, such as the Chicago Board of Trade and the New York Mercantile Exchange, to million- and billion-dollar private suits as well as government enforcement efforts.

Fought vigorously by the industry, this potential double-barreled oversight is especially important in a period of deregulation, because it frees traders from dependence on government agencies for enforcement of the laws designed to protect them.

The decision is "a very significant incentive" for self-regulation by the industry, Mark D. Young, assistant general counsel for the Commodity Futures Trading Commission, said yesterday.

Industry lawyers said the ruling could produce a flood of costly lawsuits that would merely "disrupt" the regulatory framework.

The court's reasoning yesterday was also controversial in light of the current debate about judicial "intrusions" into the legislative realm. Justice John Paul Stevens, writing for the majority, said Congress' intention to allow private suits could be inferred from its silence on the subject and because it has never stopped lower federal courts from allowing the suits. (Some parties argue similarly to show Congress' approval for denying tax exemptions to segregated private schools.)

Justice Lewis F. Powell Jr., writing for the dissenters, said Stevens' approach was judicial overreaching "incompatible with our constitutional separation of powers."

In fact, Congress is currently considering the very questions the court ruled on yesterday in Merrill Lynch vs. Curran and New York Mercantile Exchange vs. Leist.

A number of suits were already backed up in the federal courts awaiting yesterday's ruling. Many of them stemmed from the one of the most widely publicized commodities crises: the dramatic rise and fall of silver prices that shook the nation's financial markets in 1980 and sparked an investigation of the billionaire Hunt family of Texas, which was trading in silver.

The ruling revolves around commodities futures contracts: agreements to purchase or sell quantities of grain, soybeans, potatoes, silver and other items at a specified future date for a specified price. These contracts are traded on exchanges, like the New York Mercantile Exchange, by brokers similar to stockbrokers and are bought and sold both by producers of these commodities and by speculators. The speculators never actually see the commodity they trade in.

Three of the four suits involved in yesterday's ruling stemmed from a highly publicized default by two leading potato processors, who failed to deliver approximately 100 million pounds of potatoes in May, 1976. Traders with contracts for the potatoes subsequently lost their investment and filed a series of lawsuits charging price manipulation by the potato processors and negligence on the part of the New York Mercantile Exchange for allegedly failing to enforce the rules to protect traders.

The fourth suit involved in the ruling was brought against Merrill Lynch, Pierce, Fenner & Smith by customers who lost money trading in commodities futures and accused the company of mismanaging their money and making untrue statements about their investments.

The issue of availability of "private causes of action" under various laws confronts the federal courts whenever Congress has failed to be explicit on the subject, which is most of the time. In the past few years, the court has generally declined to recognize a private right to sue in such cases.

Congress was silent in 1974 when it amended the Commodity Exchange Act, revising the regulatory framework for the industry. At that time, Stevens said yesterday, many federal courts had already allowed private suits in the commodities field. Knowing this, Congress did nothing about those court rulings, he said. That, combined with inferences drawn from the debate over the amendment, "persuasively indicates that preservation of the remedy was indeed what Congress actually intended," Stevens wrote.

Joining Powell in dissent were Chief Justice Warren E. Burger and Justices William H. Rehnquist and Sandra Day O'Connor.