★ Certainty - judicial precedent means litigants can assume that like cases are treated alike, rather than judges making their own random decisions, which nobody could predict. This helps people plan their affairs.
★ Detailed practical rules - case law is a response to real situations, as opposed to statutes, which may be more heavily based on theory and logic. Case law shows the detailed application of the law to various circumstances, and thus gives more information than statute.
★ Free market in legal ideas - the rightwing philosopher Hayek, nineteen eighty two, has argued that there should be as little legislation as possible, with case law becoming the main source of law. He sees case law as developing in line with market forces: if the ratio of a case is seen not to work, it will be abandoned; if it works, it will be followed. In this way, the law can develop in response to demand. Hayek sees statute law as imposed by social planners, forcing their views on society whether they like it or not, and threatening the liberty of the individual.
★ Flexibility - law needs to be flexible to meet the needs of the changing society, and case law can make changes far more quickly than Parliament. The most obvious signs of this are the radical changes the House of Lords made in the field of criminal law, following announcing in nineteen sixty six that its judges would no longer be bound by their own decisions.
⊗ Complexity and volume - There are hundreds of thousands of decided cases, comprising several thousand volumes of law reports, and more are added all the time. With the development of the Internet, almost every decided case is available online or in legal databases. Judgments themselves are long, with many judges making no attempt at readability, and the ratio decidendi of a case may be buried in a sea of irrelevant material. This can make it very difficult to pinpoint appropriate principles.
A possible solution to these difficulties would be to follow the example of some European systems, where courts hand down a single concise judgment with no dissenting judgments. However, some of these decisions can become so concise that lawyers are required to do considerable research around the specific words used to discover the legal impact of the case, because no detailed explanation is provided by the judges.
⊗ Rigid - The rules of judicial precedent mean that judges follow a binding precedent even where they think it is bad law, or inappropriate. This can mean that bad judicial decisions are perpetuated for a long time before they come before a court high enough to have the power to overrule them.
⊗ Illogical distinctions - The fact that binding precedents must be followed unless the facts of the case are significantly different can lead to judges making minute distinctions between the facts of a previous case and the case before them, so that they can distinguish a precedent which they consider inappropriate. This in turn leads to a mass of cases all establishing different precedents in very similar circumstances, and further complicates the law.
⊗ Unpredictability - The advantages of certainty can be lost if too many of the kind of illogical distinctions referred to above are made, and it may be impossible to work out which precedents will be applied to a new case.
⊗ Dependence on chance - Case law changes only in response to those cases brought before it, so important changes may not be made unless someone has the money and determination to push a case far enough through the appeal system to allow a new precedent to be created.
⊗ Unsystematic progression - Case law develops according to the facts of each case and so does not provide a comprehensive code. A whole series of rules can be built on one case, and if this is overruled, the whole structure can collapse.
⊗ Lack of research - When making case law, the judges are only presented with the facts of the case and the legal arguments, and their task is to decide on the outcome of that particular dispute. Technically, they are not concerned with the social and economic implications of their decisions, and so they cannot commission research or consult experts as to these implications, as Parliament can when changing the law. Increasingly, the senior courts have been willing to allow interveners to make representations in the public interest during court proceedings. Such an intervener might be, for example, a charitable body, such as Liberty or JUSTICE, and it will present to the court arguments about the broader impact of the case on society, provide comparisons with practice abroad, and refer to socio-economic research in the field. In the House of Lords' last year of operation, it allowed third-party interveners to make representations in almost 1/3 of its cases.
⊗ Retrospective effect - Changes made by case law apply to events which happened before the case came to court, unlike legislation, which usually only applies to events after it comes to force. This may be considered unfair, since if a case changes the law, the parties concerned in that case could not have known what the law was before they acted. US Courts sometimes get round these problems by deciding the case before them according to the old law, while declaring that in future, the new law will prevail: or they may determine with what degree of retroactivity a new rule is to be enforced. In SW v United Kingdom (1995), two men, who had been convicted of the rape and attempted rape of their wives, brought a case before the European Court of Human Rights, alleging that their convictions violated article seven of the European Convention on Human Rights, which provides that criminal laws should not have retrospective effect. The men argued that when the incidents which gave rise to their convictions happened, it was not a crime for a man to force his wife to have sex; it only became a crime after the decision in R v R (1991). The Court dismissed the men's argument: Article 7 did not prevent the courts from clarifying the principles of criminal liability, providing the developments could be clearly foreseen. In this case, there had been mounting criticism of the previous law, and a series of cases which had chipped away at the marital rape exemption, before the R v R decision. The principle behind this is that there is no breach of the European Convention when courts clarify the law provided legal developments can be foreseen.
The same issue came before the courts again in R v C (2004). In that case the defendant was convicted in 2002 of raping his wife in 1970. On appeal, he argued that this conviction breached Article 7 and tried to distinguish the earlier case of SW against United Kingdom (1995). He said that while in SW the defendant could have foreseen in 1989 when he committed the offence that his conduct would be regarded as criminal, this was not the case in 1970. This argument was rejected by the Court of Appeal. It claimed, rather unconvincingly, that a husband in 1970 could have anticipated his development in the law. In fact, the leading text books at the time clearly stated that husbands were not liable for raping their wives.
Recent criminal cases have shown that the retrospective effect of case law can also work to the benefit of the defendant. In R v Powell and English (1999), the House of Lords clarified the law that should determine the criminal liability of accomplices. An earlier controversial case that had involved the criminal liability of an accomplice was that of R v Bentley (1953), whose story was made into a Hollywood film 'Let Him Have It'. Bentley was caught and arrested after being chased across rooftops by police. Craig had a gun and Bentley is alleged to have said to Craig, 'Let him have it.' Craig then shot and killed a policeman. Craig was charged with murdering a police officer (at that time, a hanging offence) and Bentley was charged as his accomplice. In court, Bentley argued that when he shouted, 'Let him have it', he was telling Craig to hand over his gun rather than, as the prosecution claimed, encouraging him to shoot the police officer. Nevertheless, both were convicted. Craig was under the minimum age for the death sentence, and was given life imprisonment. Bentley, who was older, was hanged. The conviction was subsequently overturned by the Court of Appeal in July 1998, following a long campaign by his family. In considering the trial judge's summing up to the jury, the Court of Appeal said that criminal liability 'must be determined according to the common law as now understood.' The common law that applied in 1998 to accomplice liability was more favourable than the common law that applied 1952. The danger in practice is that every time the common law shifts to be more favourable to defendants, the floodgates are potentially opened for defendants to appeal against their earlier convictions. To try to avoid this problem, the Criminal Justice and Immigration Act, 2008, provides that the Court of Appeal can reject as out of time references made to it by the Criminal Cases Review Commission which are based purely on a change in the common law. The Court is likely to do this where a rejection of the appeal will not cause substantial injustice.
⊗ Undemocratic - Lord Scarman pointed out in Stock v Jones (1978) that the judge cannot match the experience and vision of the legislator; and that unlike the legislator the judge is not answerable to the people. Theories, like Griffith's, which suggest that precedent can actually give judges a good deal of discretion, and allow them to decide cases on grounds of political and social policy, raise the question of whether judges, who are unelected, should have such freedom.