The Supreme Court left intact rulings the government says will destroy one of the Internal Revenue Service's best ways of catching tax cheaters.

The justices, without comment, refused yesterday to hear an IRS appeal aimed at blocking the release of documents pertaining to its Taxpayer Compliance Measurement Program.

A federal trial judge in Seattle and the 9th U.S. Circuit Court of Appeals ruled that the IRS must surrender the documents to Susan and Philip Long, a Washington couple who sued for various IRS files under the Freedom of Information Act.

The compliance program is a statistical investigatory technique devised by the IRS to measure compliance with federal tax laws. About 2 million tax returns are subjected to IRS audits each year, and the so-called TCMP is designed to select the returns of persons who are most likely to have understated their tax liability.

The court yesterday also:

Let stand a ruling that the Commodities Futures Trading Commission has the final word on halting commodities trading in a market emergency.

The justices rejected an appeal by the Chicago Board of Trade from an appeals court ruling that the commission's order suspending wheat futures trading wasn't reviewable by courts.

The commission issued an emergency order halting trading in March 1979 wheat future contracts on grounds that a small number of speculative traders threatened to corner the market, supply and demand forces were not in balance, and contracts wheat prices were distorted in comparision with the grain's value.

Cleared the way for the National Labor Relations Board to enforce its order that union representatives be given access to J. P. Stevens textile mills.

The justices denied a stay of a 4th U.S. Circuit Court of Appeals decision upholding the board's order. Stevens had asked for a stay pending high court review of its appeal.

Stevens has been battling union organizing efforts in its 81 plants in New England and the southeastern United States since the early 1960s.

The case the court acted on yesterday involved organizing attempts by the Amalgamated Clothing and Textile Workers in May and June 1976 at Stevens' Tifton, Ga., plant.

Let stand a ruling that the Seventh Amendment requires a jury in a long and complex noncriminal trial.

The court also refused to hear an appeal by International Business Machines Corp. that juries are impractical in complicated cases. IBM was appealing a 9th U.S. Circuit Court of Appeals ruling in an antitrust case involving Greyhound Computer Corp.

The case the court refused to hear yesterday stemmed from five class actions and 13 individual suits against U.S. Financial, a California-based real estate finance and title insurance company, which went into bankruptcy in 1973.

The suits alleged violations of federal securities laws and fraud in the selling of stock and unsecured bonds.

After the suits were transferred to U.S. District Court in the Southern District of California, Judge Howard B. Turrentine ruled in June 1977 that a jury was impractical because of the complex issues, the volume of materials and the projected length of the trial.

Reversed a lower court and said the Labor Department may impose civil penalties for violation of federal child labor laws.

The high court ruled in favor of Labor Secretary Ray Marshall in a case against Jerrico Inc., which runs a restaurant chain.

The lower court ruled that a 1974 federal law creating several penalities for violation of child laws was unconstitutional.

The Supreme Court ruled unanimously that the law is constitutional.