Changes
In its original version, the Act mandated that dynastic members could only marry members of other royal families of equal rank, or else the right of succession would without exception be lost for the person concerned and all his descendants. The key wording was "private man's daughter" (Swedish: enskild mans dotter), a term which in Swedish jurisprudence was understood to include all non-royals, including the aristocracy. In 1938 the statutory provision which required a spouse of royal birth was changed and the prohibition only extended to a "private Swedish man's daugther" (Swedish: enskild svensk mans dotter).
A total of five Swedish princes lost their rights of succession due to violation of that provision: Oscar in 1888, Lennart in 1932, Sigvard in 1934, Carl in 1937 and Carl Johan in 1946. There is since 1980 no statutory limitation, based on either nationality or royal rank, on whom a prince or princess can marry, apart from the fact that permission must be granted.
In 1980, the rule of succession was changed from agnatic primogeniture to full cognatic primogeniture. This means that the eldest child of the monarch, regardless of sex, is the first in line of succession. This change in effect created Victoria (born 1977) heir apparent, passing over her younger brother Prince Carl Philip (born 1979).
Read more about this topic: Swedish Act Of Succession