In Colorado, marrying your first cousin is fully legal. The state imposes no restrictions, conditions, or special requirements on first cousin marriages. This means that individuals who wish to marry their first cousin can do so without encountering any unique legal hurdles or additional paperwork.
Colorado’s laws treat first cousin marriages the same as any other marriage, making it one of the more permissive states in the U.S. regarding this issue.
Prohibited Marriages in Colorado
While Colorado law is clear and permissive about first cousin marriages, there are strict prohibitions on other close familial relationships. The state does not allow marriages between ancestors and descendants (such as parent and child or grandparent and grandchild), siblings, or between uncles/aunts and nieces/nephews, except in rare cases permitted by aboriginal customs.
These prohibitions are absolute and do not depend on whether the relationship is by whole-blood or half-blood, or whether either party is able to have children.
How Colorado Compares to Other States
Colorado is among 18 states, plus the District of Columbia, where first cousin marriage is completely legal. In contrast, 24 states prohibit first cousin marriages outright, and eight others only allow it under specific circumstances, such as age or infertility.
For example, in Arizona and Illinois, first cousins can marry only if both parties are beyond a certain age or if one is infertile. Colorado stands out for its lack of such stipulations, which has led some out-of-state couples to choose Colorado as a destination for legal cousin marriage.
Requirements for Marriage in Colorado
Aside from the familial relationship restrictions, Colorado’s general marriage requirements are straightforward. Both parties must be at least 18 years old, or at least 16 with parental or guardian consent. Neither party can be currently married or in a civil union with someone else.
If a marriage is entered into that is prohibited by law, it is considered void and subject to annulment, which is legally termed a “declaration of invalidity of marriage” in Colorado.
Social and Cultural Context
Although cousin marriage is legal in Colorado, it is not particularly common, and social attitudes toward the practice can vary. The law, however, is unambiguous: first cousin marriages are permitted and recognized in the state, and couples who choose this path are afforded the same legal rights and responsibilities as any other married couple.
Colorado law allows first cousin marriages without restriction, making it one of the more open states on this issue. As long as all other legal requirements for marriage are met, first cousins are free to marry in Colorado.
Sources
[1] https://www.graham.law/blog/marry-your-cousin-colorado-family-marriage/
[2] https://thewrangler.com/is-it-illegal-to-marry-your-cousin-in-colorado-heres-what-the-law-says/2025/06/09/
[3] https://kekbfm.com/colorado-marry-your-cousin/
[4] https://k99.com/cousin-marriage-colorado/
[5] https://95rockfm.com/colorado-marry-first-cousin/
