Presumably we're talking about the Salic Law.
The Salic law was, strictly speaking, the complete legal code of the Salian or Western Franks who conquered Gaul in the 5th century. It had great authority because of the dominance of the Franks in Western Europe, and influenced many later Germanic codes. It was set down in writing (in Latin) in the reign of Clovis in the early sixth century. It was primarily a criminal code, with a long list of penalties for various crimes, but included some civil provisions.Among these was the rule that daughters could not inherit land.
Much later, this provision (the "Salic law of succession") was invoked in dynastic disputes to deny the right of women to reign.
In France,when the direct male Capetian line died out with Charles IV (son of Philip the Fair) in 1328, the French nobles proclaimed Philip of Valois (Philip the Fair's nephew, the son of his brother) as king. The claim of Edward III of England, who was Philip the Fair's grandson, was rejected since he was the son of Philip's daughter and not the son of his son. During the 14th and 15th centuries French jurists, justifying the exclusion from the throne of women and their descendants, sometimes mentioned the Salic law among their arguments. But the main reason was said to be custom. It was also argued that kingship had a priestly character and therefore could not be exercised by a woman.
As time went on the Salic law was given more weight in legal arguments.In 1593 it was expressly invoked to deny the claim to the French throne of Isabella, infanta of Spain. From then on it was regarded as a fundamental law of the kingdom.
In Spain, the Salic law of succession was promulgated by Philip V (the first King of Spain to come from the French Bourbon dynastry) in 1713, but rescinded by Ferdinand VII in 1830.
In Savoy it was introduced by Amadeus V in the early 14th century.
The position in the Holy Roman Empire is not clear to me. The Imperial crown was technically an elective office but from the late 15th century was in fact held hereditarily by the Hapsburgs. The same was perhaps true of some of the other Hapsburg crowns. Charles VI's Pragmatic Sanction ensured that his daughter, Maria Theresa, succeeded to the crowns of Austria, Hungary and Bohemia, but she could not rule the Empire: the Imperial crown was held successively by her husband Francis (Franz) I and her son Joseph II.
In Hanover the Salic law applied until Hanover was absorbed into Prussia after the war of 1866. Hence, in 1837, King William IV of the United Kingdom, who was also Elector Wilhelm Heinrich of Hanover,was succeeded by Victoria in Britain but by Ernest Duke of Cumberland in Hanover.
The Salic law of succession was never recognized in England, Scotland or in the Scandinavian countries.
This is based on Encyclopaedia Britannica and the Oxford Companion to Law. It suggests that, where women and the descendants were barred from succeeding to thrones, the Salic law was said to be at least one of the reasons.