Legal Definitions - forbidden degree

A forbidden degree refers to a relationship between two individuals that is too close, either by blood (known as consanguinity) or by marriage (known as affinity), to allow them to legally marry. Laws establishing forbidden degrees are in place to prevent incest, protect family structures, and sometimes to address genetic concerns, varying slightly by jurisdiction.

Here are some examples illustrating the concept of a forbidden degree:

• Example 1: Direct Blood Relation

  A man and his biological daughter wish to marry. This relationship falls within a forbidden degree due to direct consanguinity (a direct bloodline relationship). Such a marriage would be legally void and often considered a criminal offense in virtually all jurisdictions, reflecting universal societal and legal prohibitions against incest.

• Example 2: Collateral Blood Relation

  A brother and his sister, who share the same parents, decide they want to marry. This relationship is also a forbidden degree due to collateral consanguinity (sharing a common ancestor, but not in a direct line). Laws universally prohibit marriage between full or half-siblings, making any such union legally invalid.

• Example 3: Relation by Marriage (Affinity)

  After a divorce, a man seeks to marry his former stepdaughter (his ex-wife's biological daughter from a previous relationship). Even though there is no blood relation between them, many legal systems consider the relationship between a stepfather and stepdaughter to be a forbidden degree for marriage based on affinity. This prohibition acknowledges the familial bond created by the prior marriage and aims to prevent disruption of established family roles, even after the original marriage has ended.