Investigation, as an evidence-gathering process, is integral to litigation. Investigation is the period of fact-gathering that precedes a trial, the decision to charge, or the decision to sue.
Typical investigation tasks include examining financial, medical and administrative records; interviewing favorable witnesses while seeking to understand the testimony likely to be offered by adverse witnesses; and researching expert opinions.
Investigation is how a case is built, influences whether an attorney believes that a client has a case, and can change the outcome of a trial. Both civil and criminal trials are centered on presenting a story to the judge and jury. This story is built by facts found during an investigation.
In criminal law, both district attorney offices and criminal defense firms employ full-time investigators. Before civil firms advise their clients on the likely success of their claims, they engage in extensive investigation to determine what story they can tell in court. Criminal defense firms engage in investigation before advising a client to take or reject a plea deal.