J. D.
Abbreviation for "juris doctor" or "doctor of jurisprudence" and the formal name given to the university law degree in the United States. It is a prerequisite to most bar admission exams.

Jactitation
A false boast designed to increase standing at the expense of another. This used to form the basis of an ancient legal petition called "jactitation of marriage" wherein a person could be ordered by the courts to cease claims of being married to a certain person when, in fact, they were not married. The tort of slander of title is a form of jactitation.

Joint custody
A child custody decision which means that both parents share joint legal custody and joint physical custody. This is not very common and many professionals have taken to referring to "joint legal custody but sole maternal physical custody" as "joint custody".

Joint tenancy
When two or more persons are equally owners of some property. The unique aspect of joint tenancy is that as the joint tenancy owners die, their shares accrue to the surviving owner(s) so that, eventually, the entire share is held by one person. A valid joint tenancy is said to require the "four unities": unity of interest (each joint tenant must have an equal interest including equality of duration and extent), unity of title (the interests must arise from the same document), unity of possession (each joint tenant must have an equal right to occupy the entire property) and unity of time: the interests of the joint tenants must arise at the same time.

Judicial review
When a court decision is appealed, it is known as an "appeal." But there are many administrative agencies or tribunals which make decisions or deliver government services of one sort or another, the decisions of which can also be "appealed." In many cases, the "appeal" from administrative agencies is known as "judicial review" which is essentially a process where a court of law is asked to rule on the appropriateness of the administrative agency or tribunal's decision. Judicial review is a fundamental principle of administrative law. A distinctive feature of judicial review is that the "appeal" is not usually limited to errors in law but may be based on alleged errors on the part of the administrative agency on findings of fact.

Jure
Latin, from Roman law: by right, under legal authority or by the authority of the law. A variation, "juris" means "of right" or "of the law." See jurisprudence below which means "science of the law."

Jurisdiction
legal authority which a court has over particular persons, certain types of cases, and in a defined geographical area

Jurisprudence
Technically, jurisprudence means the "science of law". Statutes articulate the bland rules of law, with only rare reference to factual situations. The actual application of these statutes to facts is left to judges who consider not only the statute but also other legal rules which might be relevant to arrive at a judicial decision; hence, the "science". Thus, jurisprudence" has come to refer to case law, or the legal decisions which have developed and which accompany statutes in applying the law against situations of fact.

Jury
A group of citizens randomly selected from the general population and brought together to assist justice by deciding which version, in their opinion, constitutes "the truth" given different evidence by opposing parties.

Jus
Latin: word which, in Roman law, meant the law or a right. Also spelt "ius" in some English translations. For example, public law was called "jus publicum" and private law was called "jus privatum."

Jus spatiandi et manendi
Latin: referring to a legal right of way, and to enjoyment, granted to the public but only for the purposes of recreation or education, such as upon parks or public squares. Very similar to an easement of which some courts have said a jus spatiandi is a special type.

Justice
Fairness. A state of affairs in which conduct or action is both fair and right, given the circumstances. In law, it more specifically refers to the paramount obligation to ensure that all persons are treated fairly. Litigants "seek justice" by asking for compensation for wrongs committed against them; to right the inequity such that, with the compensation, a wrong has been righted and the balance of "good" or "virtue" over "wrong" or "evil" has been corrected.

Juvenile Law
the area of law that deals with juvenile delinquency proceedings or other court proceedings involving minors (those under the age of 18)