There are advantages and disadvantages of the system of judicial precedent as it has developed in English law.

The advantages are as follows:

Certainty:
Liberty to decide each case as you think right without any regard to principles laid down in previous similar cases would only result in a completely uncertain law in which no citizen would know his rights or liabilities until he knew before what judge his case would come and could guess what view that judge would take on a consideration of the matter without any regard to previous decisions
However, it is necessary for any system of law to have a degree of flexibility, and to the extent that law is flexible it cannot be certain, and vice versa. The courts, particularly the House of Lords, must therefore always balance the need for certainty against the need for flexibility in any particular case.

Possibility of growth.
The system allows for new rules to be established and old rules to be adapted to meet new circumstances and the changing needs of society. Where a precedent is considered to be particularly valuable its scope can be extended in later cases: conversely, where a precedent is felt to be defective, its scope can be restricted by the process of distinguishing mentioned above.
Wealth of detailed rules. No code of law could be devised which would provide the wealth of detail to be found in English case-law.

Practicality.
The rules of English case-law do not derive from a particular theory of law, and do not attempt to deal with hypothetical circumstances. They are the result of the consideration of real situations which have come before the courts.

The disadvantages of the system of judicial precedent are:
Rigidity.
Once a rule has been laid down it is binding even if the decision is thought to be wrong, and altercation, other than by distinguishing, which is less than wholly satisfactory, is difficult. This disadvantage is modified to the extent that the House of Lords is not bound by its own previous decisions, but people are reluctant to bring appeals before the House of Lords because of the enormous expense involved, particularly bearing in mind that the House will not overrule its own previous decision except in the most compelling circumstances. The possibility that case-law will be abrogated or modified by legislation alleviates the disadvantage of rigidity to some degree, but in practice it is rare for the legislation to interfere with case-law.

Bulk and complexity.
There is so much law that no one can learn all of it. There is a danger that even an experienced lawyer may overlook some important rule in any given case. This is particularly so with those branches of law which have been developed mainly by case-law, as, for example, the law of torts.

Slowness of growth.
The system depends on litigation for rules to emerge. As litigation tends to be slow and expensive the body of case-law cannot grow quickly enough to meet modern demands.
Where it is felt that a particular case has long been a precedent operates unfairly, or where the law on an important point is unclear, it is argued by some that appeals to the House of Lords should be financed at public expense, as it is inequitable that the law should be developed or clarified at the expense of private litigants. (It is worth noting, however, that many cases heard in the House of Lords are in effect financed by public funds, where the parties are either legally aided or are bodies, such as the Commissioners of Customs and Excise, who are financed entirely out of public funds).

See Also:
Judicial Precedent Case Law
History of Precedent
Rules of Precedent: Civil Courts
Law Reports