26 May 1978,
Adultery ceased to be a crime in the Spanish State. Until then, if a married woman went to bed with a man who had no husband, she could have been sentenced to six years in prison for adultery. Hundreds were condemned and imprisoned for these acts. In 1977, for example, 45% of women prisoners in Spain were in prison for abortion, family abandonment, adultery or infanticide.
Source:
Amparo Rubiales, A woman of women (Aguilar).