Legal research is the process of identifying and retrieving information necessary to support legal decision-making.  Legal research begins with an analysis of the facts of a problem and concludes with the application and communication of the results of the investigation.

Legal research is one of the basic activities in the practice of law.  Legal research is the core of any legal action, as legal actions are based on the construction of legal arguments, and legal arguments are constructed by the support gained through research.

Legal research is drawn from three kinds of resources: primary, secondary, and evidential.  Primary resources generally refer to the rule of law.  Secondary resources are anything for which supports legal research other than the specific words of the law, and as a result it can be a very broad category.  Evidential refers to the physical, material, or testimonial elements that become part of a case and subsequently part of a legal argument; in simple terms, evidence.

Legal research may be carried out for varied reasons.  Some use it to identify the sources of law applicable to understanding a legal problem, and then find a solution to the problem that has been identified.  It is apparent that lawyers are expected to conduct factual and legal research in an effective manner because of long term implications on their clients.

Generally, there are four stages of legal research:

• Search for the facts of a case –  First determine the factual basis of the problem.  This search for the facts of a case is not confined wholly to events and objective things, but inevitably, involves a hypothesis as to the legal bearing of the facts.

• Finding pertinent statutes, cases and administrative rulings and regulations –  The second stage of legal research requires the finding of the law in the jurisdiction involved, having some relation to the facts of the case, and which fit into the hypothesis upon which you are for the moment working.

• The third stage follows, in which you intensively examine the assembled legal material, classify it with critical care, and make sure that it corresponds to the theory of the case that you are tending to adopt for brief writing.

• The fourth stage is the one in which you deal not only with technical legal material, but combine it also with all other elements which affect your theory of the case, throw all your facts, legal and otherwise, into legal perspective, determine what your prediction of the possible result of argument will be, and choose the strategy and tactics of your scheme of advocacy.

The U.S. legal system is based on precedent — that is, decided court cases — in conjunction with statutes and common law.  Therefore, the function of legal research typically is to find out how previous courts have decided cases with similar fact patterns.

An attorney may review statutes, caselaw, and secondary authority before deciding how to proceed with a case. Since the law is based on precedent, caselaw with a similar fact pattern can give attorneys an idea of how things may play out in court.

The task of a lawyer is to present his case with the support of existing statutes and cases already decided.  The essence of good legal drafting is to briefly recite the facts of the case, explain the applicable law, apply the law to the facts of the case, and explain how his motion will succeed.  An important reason to do legal research is to find all viable legal theories to include in the complaint and to avoid legal theories that have failed in the past for good reasons that are explained in prior cases.