In some jurisdictions, an assessor is a judge's or magistrate's assistant. This is the historical meaning of this word.
In common law jurisdictions, assessors are usually non-lawyers who sit together with a judge to provide either expert advice (such as on maritime matters) or guidance on local practices. The use of assessors nowadays is quite rare. In some jurisdictions, such as Fiji, assessors are used in place of juries. An assessor's opinion or view of a case is not binding on a judge.
The term "assessor" is also very generally applied to persons appointed to ascertain and fix the value of rates and taxes, and in this sense the word is used in the United States (see Assessor (property)).
In France and in all European countries where the civil law system prevails, the term assesseur is applied to those assistant judges who, with a president, compose a judicial court.
In Germany, Rechtsassessor ("assessor of law") is a title held by graduates of law who have passed both the first and the second of the two state exams (finishing law school and a two-year legal clerkship) qualifying for a career in a legal profession such as judge or prosecutor, attorney at law or civil-law notary.
In Norway, the title was used for any judge before 1927.
In Sweden, a judge who has been a district court clerk for two years, an appeal court clerk for at least one year, a deputy district judge for at least two years and a deputy appeal court judge for one year gets, if he or she is approved, the title assessor. Hovrättsassessor = assessor of the civil and criminal appeal court. Kammarrättsassessor = assessor of the administrative appeal court. Having the degree of assessor is the most common way of getting a constitutionally protected position as a judge (ordinarie domare), but increasingly advocates, prosecutors and doctors of law are also appointed to these positions.
In the former Soviet Union, a judge presiding at trial is assisted by two "people's assessors" drawn much like jurors from citizens in the community. They do not rule on matters of law but can allow or deny objections. When the trial is completed the judge and people's assessors decide on a verdict.
In People's Republic of China, "people's assessors" can form judicial panel together with professional judges to try cases. People's assessors are selected from the residents within the court's jurisdiction. Besides a single judge, judicial panels can consists of one judge and two assessors or three judges and four assessors to try cases. The people's assessors mostly enjoy the same rights as professional judges, but they should only vote on the findings of the fact, not on the matter of law.
Serious criminal trials are conducted by a judge sitting with four lay assessors.
S.53 of the High Court Ordinance provides that a judge in the Court of First Instance may sit with one or more assessor who holds special qualifications. It is not normal practice for the court to sit with assessors.
In serious criminal cases (such as murder) appearing before the High Court, two assessors may be appointed to assist the judge. Assessors are usually advocates or retired magistrates. They sit with the judge during the court case and listen to all the evidence presented to the court. At the end of the court case they give the judge their opinion. The judge does not have to listen to the assessors' opinions but it usually helps the judge to make a decision. The assessors may also only make decisions on facts, not on the law, which is solely the authority of the judge.