Legal Definitions - alieni juris

Alieni juris is a Latin legal term, primarily originating from Roman law, that describes an individual who is legally subject to the power or authority of another person. Essentially, it means someone does not possess full legal independence and their actions or property may be controlled by someone else.

Here are some examples to illustrate this concept:

• Example 1: A Minor Child

  Imagine a 14-year-old who wants to purchase a significant item, like a piece of real estate or a car, and sign the necessary contracts. In most legal systems, this child would be considered alieni juris. They are legally under the authority of their parents or legal guardians. The child cannot independently enter into binding contracts, own property in their own name without adult supervision, or make many other significant legal decisions. Their parents or guardians hold the legal power to act on their behalf, making the child subject to another's authority.

• Example 2: An Adult Under Guardianship

  Consider an adult who, due to a severe cognitive impairment or mental illness, has been declared legally incapacitated by a court. The court then appoints a guardian to manage their financial affairs and make personal decisions for them. This adult would be considered alieni juris. They are no longer legally independent; their actions and property are subject to the authority and decisions of their court-appointed guardian, who acts in their best interest but holds the legal power.

• Example 3: Historical Roman Family Law

  In ancient Roman law, an adult son (known as a filius familias) who was still under the absolute legal power of his father (patria potestas) was considered alieni juris. Even if the son was an adult, married, and had his own children, he did not have full legal independence. Any property he acquired legally belonged to his father, and his father had significant control over his legal actions and personal life. The son remained alieni juris until his father died or formally emancipated him, at which point he would become sui juris (of his own right).