Seriatim is a Latin term that means "in series". In the legal world, a court uses the term to indicate that it is addressing more than one legal issue in a particular order. For instance, a court might respond to three legal issues in its decision in the same order as the parties originally presented them.
Another variation is seriatim opinion, which occurs when more than one judge renders a written opinion or decision as opposed to the typical practice of one judge issuing the opinion on behalf of the court. In most cases, a court issues this type of opinion when there is not a majority opinion or when one or more judges disagree as to what the ultimate decision of the court should be. This could be a plurality opinion, where the margin between the judges’ decisions is narrow, or simply judges reaching the same result, but using different reasoning. In the United States, writing separate opinions was common practice for the United States Supreme Court until Chief Justice John Marshall discontinued this practice under the theory that the Court would have more of an effect if it spoke as one voice rather than as the multiple voices of several judges.
Ad seriatim is another variation, which translates to “one after another”. In a legal situation, a group of people might file a series of lawsuits in court one after another. Alternatively, a court might issue a series of opinions on a particular legal issue one after another.
Courts, lawyers, and others in the legal community traditionally used the term seriatim in court opinions and other legal writings. The term has fallen out of use because the courts have begun using less archaic language and more plain English terminology, which is easier for lay people to understand. Today it would be rare to find a phrase containing the word seriatim in any routine legal document or pleading.
Robert’s Rules of Order, the traditional format for conducting meetings of organizations, also refers to the concept of seriatim as the group faces a proposition consisting of several different sections, paragraphs, or resolutions. These rules provide that the group should consider a multi-layered proposition section by section. In other words, the rules direct the group to analyze and render a decision on each portion of the proposition independently as opposed to simply considering the proposition as a whole.