The Supreme Court will review the constitutionality of a congressional law designed to prevent clergymen and religious organizations in the District of Columbia from using, improper pressure to obtain "deathbed" bequests from dying persons.

The case invoives a 90-year old widow with a $380,000 estate who died in 1972. Twenty-one days before her death, she willed one-third to Calvary Baptist Church and another third to St. Matthew's Roman Catholic Catheoral. The final third went to Johns Hopkins University Medical School.

Surviving relatives of the widow, Sallye Lispscomb French, sought to have the bequests ruled illegal on the basis of an 1866 law in which Congress invalidated deathbed bequest here if made to religious leaders or groups less than 30 days before death.

Seven states have [WORD ILLEGIBLE] tougher laws that bar bequest [WORD ILLEGIBLE] charitable groups - not [WORD ILLEGIBLE]churches - within certain [WORD ILLEGIBLE] death.

There was no evidence that either Calvary Baptist or St. Matthew's had tried to influence Mrs. French to leave money to them, according to court papers. In wills executed in 1960 and 1963, she had made bequests to both Baptist and Roman Catholic organizations.

In a ruling in February, 1975, then D.C. Superior Court Judge Theodore R. Newman Jr. held the District law unconstitutional.

"No national basis has been shown for the distinctive treatment of religious . . . versus nonreligious" bequests, Newman said.

Neither has a compelling reason been shown for the 1866 law's abridgment of the Constitution's guarantees of religious freedom and of due process, Newman said.

The D.C. Court of Appeals affirmed Newman's ruling last November, Monday, the Supreme Court said it will hear arguments on the case.