Arguing a client's case before a judge or jury in a court of law is the traditional province of the barrister in England, and of advocates in some civil law jurisdictions. However, the boundary between barristers and solicitors has evolved. In England today, the barrister monopoly covers only appellate courts, and barristers must compete directly with solicitors in many trial courts. In countries like the United States that have fused legal professions, there are trial lawyers who specialize in trying cases in court, but trial lawyers do not have a de jure monopoly like barristers.
In some countries, litigants have the option of arguing pro se, or on their own behalf. It is common for litigants to appear unrepresented before certain courts like small claims courts; indeed, many such courts do not allow lawyers to speak for their clients, in an effort to save money for all participants in a small case. In other countries, like Venezuela, no one may appear before a judge unless represented by a lawyer. The advantage of the latter regime is that lawyers are familiar with the court's customs and procedures, and make the legal system more efficient for all involved. Unrepresented parties often damage their own credibility or slow the court down as a result of their inexperience.