In legal terms, what can a witness testify about?

A witness can only testify about what they have personally seen or heard because this is grounded in the principles of firsthand knowledge and reliability in legal proceedings. This requirement ensures that testimony is based on direct experience rather than secondhand information or speculation, which could introduce inaccuracies or biases.

Testimony based on personal observation is more credible, as it allows the fact-finder—like a judge or jury—to assess the accuracy of the information being provided. This restriction is key to maintaining the integrity of the legal process, as it prevents the introduction of hearsay or conjecture, which could distort the truth of the matter being adjudicated.

While various types of information can be relevant to a case, only firsthand accounts fulfill the criteria for admissible testimony in court. This eliminates the potential confusion and unfairness that could arise from allowing opinions, assumptions, or unverified recollections to influence legal outcomes.