Define: Ipse Dixit

Ipse dixit is a Latin phrase meaning “he himself said it.” In legal contexts, it refers to a statement or assertion made without any supporting evidence or authority beyond the speaker’s own opinion or assertion.

Ipse dixit may be used in legal arguments when a party relies solely on the authority or opinion of an individual without providing any independent evidence or legal precedent to support their position.

No, Ipse Dixit is generally not considered a valid form of legal argumentation in itself. Legal arguments should be supported by relevant legal authority, evidence, or precedent to be persuasive and credible.

Some examples include:

• Asserting a legal principle or interpretation without citing applicable statutes, case law, or legal commentary.
• Relying solely on the opinion or expertise of an individual without corroborating evidence or expert testimony.
• Making unsupported assertions about the facts of a case without providing documentary evidence or witness testimony.

Ipse Dixit arguments can be challenged by requesting the party making the assertion to provide supporting evidence, legal authority, or precedents to substantiate their claim. Alternatively, opposing counsel may argue that the assertion lacks credibility or is inconsistent with established legal principles.

The risks of relying on Ipse Dixit include:

• Undermining the persuasiveness and credibility of the argument.
• Failing to meet the burden of proof required in legal proceedings.
• Inviting challenges and skepticism from opposing parties, judges, or juries.
• Leading to adverse outcomes or unfavourable rulings if the unsupported assertions are not accepted by the court.

Expert witnesses should avoid using Ipse Dixit in their testimony and instead rely on established principles, methodologies, and empirical evidence to support their opinions. Courts expect expert testimony to be based on reliable methods and data rather than mere assertions.

Attorneys can avoid Ipse Dixit by conducting thorough legal research, citing relevant statutes, regulations, case law, and scholarly commentary to support their arguments, and presenting factual evidence and expert testimony where appropriate.

Judges have a duty to assess the validity and credibility of legal arguments presented in court, including identifying and addressing Ipse Dixit assertions by requiring parties to provide substantiating evidence or legal authority.