"Costume GENERAL PRINCIPLES (1) The effect of nudity or semi-nudity upon the normal man or woman, and much more upon the young person, has been honestly recognized by all law-makers and moralists. (2) Hence the fact that the nude or semi-nude body may be beautiful does not make its use in the films moral. For in addition to its beauty, the effect of the nude or semi-nude on the moral individual must be taken into consideration. <br (3) Nudity or semi-nudity used simply to put a “punch” into a picture comes under the head of immoral actions as treated above. It is immoral in its effect upon the average audience. (4) Nudity, or semi-nudity is sometimes apparently necessary for the plot. Nudity is never permitted. Semi-nudity may be permitted under conditions. PARTICULAR PRINCIPLES (1) The more intimate parts of the human body are the male and female organs and the breasts of a woman. (a) They should never be uncovered. (b) They should not be covered with transparent or translucent material. (c) They should not be clearly and unmistakably outlined by the garment."
January 1, 1970
https://en.wikiquote.org/wiki/Hays_Code