The board of the American Medical Association has decided to throw the weight of the AMA into the battle against legislation in Congress that would establish that human life begins at conception.

Late last week, the board of trustees voted to send two spokesmen to oppose the two nearly identical bills -- called the "Human Life" legislation -- at hearings in Congress in the middle of June. The mesures, introduced in the House and Senate, would effectively outlaw abortion by making it murder. Opponents also claim that passage would outlaw several forms of contraception. o

"We will speak in opposition to the bill (introduced in the Senate)," said James Sammons, executive director of the AMA. Elaborating, a spokesman for Sammons said, "The legislation is founded on the idea that a scientific consensus exists that life begins at the time of conception. We will go up there to say that no such consensus exists."

In addition, the spokesman said, the idea that life begins at conception creates great legal problems in any pregnancy, since it would mean that two legal persons exist in the same body, and most any medical treatment for the woman would entail a risk for the fetus. Under the bills, he said, a fetus would have legal rights, raising the possibility that treatment of the mother could be withheld.

The AMA, the nation's largest organization of doctors with a membership of 240,000 physicians, will be one of the most influential groups to oppose the bills, and the group that has the largest lobbying organization in Washington of those in opposition.

Others who have declared their opposition include the Natinal Academy of Sciences, the American Public Health Association, six former attorneys general and a Boston group that includes several hundred scientists and six Nobel laureates.

Hearings on the Senate version of the bill were began last spring in a Senate Judiciary subcommittee. The AMA was not invited to testify at those hearings, according to an AMA spokesman. But the association has been invited to speak at the new rounds of hearings to be held by Sen. John P. East (R-N.C.).

The AMA board of trustees took its action in a meeting last week preliminary to the association's convention that began here today.

In other action at the beginning of the meeting, delegates representing 21,000 medical students in the country voted to protest the nomination of Dr. C. Everett Kopp as surgeon general of the United States.

"This is obviously a political patronage appointment," said Ronald M. Davis, a University of Chicago medical student who introduced the resolution. "We recognize this is part of the political game, to make appointments on the basis of loyalty, or on the basis of a position on some issue. But the job of surgeon general shouldn't be one of those kinds of appointments. This shouldn't be a political job," he said.

The resolution, which did not refer to Koop by name but only as the "present surgeon general nominee," said the position "must remain outside of political patronage if the scientific reports and official pronouncements issued over his imprimatur (e.g. smoking, nutrition, legionnaire's disease) are to maintain credibility. . . ."

The resolution also said Koop has little or no training or experience in the field of public health.

The student delegates also passed a laundry list of other resolutions on controversial topics, which will now go before the House of Delegates of the AMA for consideration.

The students also voted in favor of the Equal Rights Amendment for women, voted to oppose all federal subsidies to the tobacco industry, and voted for stricter handgun control.

The House of Delegates of the AMA will vote on these and about 175 other issues here Tuesday and Wednesday.