The American Catholic Bishops adopted a detailed statement yesterday spelling out their opposition to capital punishment for both moral and practical reasons.

The 3,500-word statement acknowledges the need for society to punish criminals, make restitution to their victims where possible and to protect the public from potentially dangerous criminals. But such needs neither "require nor . . . justify taking the life of the criminal, even in cases of murder," the statement said.

In defending the statement, which was adopted by a vote of 145 for, 31 against and 41 abstentions, Bishop Edward D. Head of Buffalo said that the climate of public opinion in America today favors a return to -- rather than abolition of -- the death penalty. Citing the murders of blacks both in his own city and in Atlanta, Head said he had "full recognition of the seriousness of the problem."

But he said that the Catholic statement was "grounded in the belief that the taking of life should not be answered by more violence in the taking of [more] life."

The statement includes many of the arguments frequently offered in opposition to capital punishment: the possibility of an irremediable mistake; the inequities in the criminal justice system for indigent defendants; the fact that execution of a criminal precludes both the possibility for reform and the opportunity for the criminal to make some restitution for his crime. It also challenges the contention that capital punishment serves as a deterrent to crime.

The bishops defend their opposition to capital punishment as a logical extension of their opposition to abortion and "a manifestation of our belief in the unique worth and dignity of each person, a creature made in the image and likeness of God."

The bishops said they did not "wish to equate the situation of criminals convicted of capital offenses with the condition of the innocent unborn or of the defenseless aged or infirm, but we do believe that the defense of life is strengthened by eliminating exercise of a judicial authorization to take human life."

Another detailed position paper adopted by the bishops in the closing hours of their four-day meeting here sought to spell out the relationship of Catholic colleges and universities to the church.

A key section said the "academic freedom and institutional independence" of Catholic schools were "essential components of educational quality and integrity."

Urging "academic excellence" on all Catholic institutions, the statement counsels that the "policies, standards, curricula, governance and administration" of such schools "should accord . . . with the norms of quality accepted in the wider academic community."

The statement stresses the importance of a strong liberal arts curriculum, particularly in undergraduate institutions, but cautions that a Catholic school "must go beyond the secular humanism which also emphasizes the liberal arts. . . An institution's Catholic identity is largely expressed in a curriculum that shows how the values of the Judaeo-Christian view of life illuminate all fields of study and practice."

In a section on theology, the paper states that a grounding in Catholicism's theological heritage "is a moral obligation owed to Catholic students." At the same time, it continues, the Catholic school must take into account the maturity level of the students and "be cautious about private speculation of a kind that might undermine the students' foundations of faith in God's revealed truth."

The bishops saved for executive session a discussion on implementing last summer's decision to admit disgruntled priests who have split from the Episcopal Church because they oppose women priests and want to retain the 1928 version of the Book of Common Prayer.

Precise conditions for admission of the former Episcopalians have not been announced by the Roman Catholic Church. It was learned yesterday, however, that with the exception of a few portions from the 1928 prayer book, they will be required to follow the authorized Roman liturgy, including the prayers that were revised by the bishops earlier this week to make them more inclusive of women.