June 7, 1983

The Nicaraguan Government expelled three American diplomats today, charging one with overseeing a ''macabre plot'' to kill or incapacitate the Foreign Minister. All three, according to Lenin Cerna, the Government's security chief, were using diplomatic cover while working for the Central Intelligence Agency. He said they were building a ''counterrevolutionary network'' whose members were to have formed ''terrorist commando squads to carry out attacks on our leaders.'' The United States Embassy rejected the charges ''in most emphatic terms'' and asked the Nicaraguans to rescind the expulsion orders, which it said ''directly contravene the most basic norms of diplomatic practice.'' An embassy spokesman, Gilbert Callaway, described the charges as ludicrous and ''all lies.''

The Reagan Administration plans to liberalize the criteria for paying Social Security disability benefits to people with physical or mental handicaps, Administration officials said today. The announcement, they said, is to be made this week by Margaret M. Heckler, the Secretary of Health and Human Services. It comes in response to criticism by members of Congress of both major political parties, who denounced the termination of benefits for people with obvious disabilities. The steps contemplated by the Administration, described by one Health and Human Services official as a ''capitulation'' to the critics, would restore some of the policies that prevailed before President Reagan took office. But it appears that the rules would still be stricter than in the Carter Administration. The new measures would not alter the 1980 law under which disability beneficiaries must be re-examined at least once every three years. The Social Security Administration began conducting those reviews in March 1981, after Mr. Reagan took office.

The Supreme Court upheld the ''windfall profits'' tax on decontrolled oil, providing a substantial victory for the Treasury. The tax has yielded about $30 billion since 1980 and is expected to yield that much more over the next six years. (Page D1.) The Justices also ruled that Federal regulators need not weigh environmental consequences of waste disposal in licensing new nuclear plants. (B7.) Speaker of the House Thomas P. O'Neill Jr. proposed that the tax cut due to take effect July 1 be limited to $700 for each taxpayer. The proposal drew a political battleline with President Reagan, who has promised to veto any effort to tamper with the reduction in tax rates. Mr. O'Neill stressed that his proposal is meant to maintain a relatively heavier tax burden on wealthier citizens. (A1.)

A particularly poignant and troubling problem in the medical profession is that of the doctor whose easy access to drugs leads to his own addiction. What follows is the story of Dr. William J. Farley, one of the rare physicians who has been willing to reveal his experience. When William Farley was growing up in Trenton, Ontario, he had an extraordinarily intimate view of medicine. His great-grandfather, grandfather and father were physicians in the same town about 100 miles east of Toronto, and his grandfather was president of the Ontario Medical Association. But he saw a sordid side of medicine. His mother, a nurse, was addicted to morphine, alcohol, codeine and other drugs, he said. Sometimes she took doses so large she had to be treated in a hospital emergency room. More than once her reactions were so severe that the young Farley was told his mother was on the verge of death.

The Pillsbury Company said yesterday that it would acquire Haagen-Dazs, a family-owned ice cream chain with an elite image, for an undisclosed amount of cash and notes. William H. Spoor, Pillsbury's chairman, who was in New York yesterday to make the announcement, said that his company had been searching for acquisition targets for months to round out its diversified food business. ''We spent weeks going through the 8,000 companies'' on our list, Mr. Spoor said. Haagen-Dazs, he said, had the elements that Pillsbury was looking for, including a franchise network of 244 ice cream stores, strong supermarket presence and corporate growth of about 30 percent a year.