Fellatio is legal in most countries. Laws of some jurisdictions regard fellatio as penetrative sex for the purposes of sexual offenses with regard to the act, but most countries do not have laws which ban the practice, in contrast to anal sex or extramarital sex. In Islamic literature, the only forms of sexual activity that are consistently explicitly prohibited within marriage are anal sex and sexual activity during menstrual cycles. However, the exact attitude towards oral sex is a subject of disagreements between modern scholars of Islam. Authorities considering it "objectionable" do so because of the penis's supposedly impure fluids coming in contact with the mouth. Others emphasize that there is no decisive evidence to forbid oral sex.
Nancy Friday's book, Men in Love – Men's Sexual Fantasies: The Triumph of Love over Rage, suggests that swallowing semen is high on a man's intimacy scale. The man receiving fellatio receives direct sexual stimulation, while his partner may derive satisfaction from giving him pleasure. Giving and receiving fellatio may happen simultaneously in sex positions like 69 and daisy chain.