The common law is a system of law that prevails in England and in countries colonized by England. The name is derived from the medieval theory that the law administered by the king’s courts represented the common custom of the realm, as opposed to the custom of local jurisdiction that was applied in local or manorial courts. In its early development common law was largely a product of three English courts—King’s Bench, Exchequer, and the Court of Common Pleas—which competed successfully against other courts for jurisdiction and developed a distinctive body of doctrine. The term common law is also used to mean the traditional, precedent-based element in the law of any common-law jurisdiction, as opposed to its statutory law or legislation and also to signify that part of the legal system that did not develop out of equity, maritime law, or other special branches of practice. (Common Law – ENCYCLOPEDIA)
Judicial practice of statutory interpretation was probably attributable to a shared sense of institutional enterprise between the judiciary and legislature. The point is not the familiar one that judges shared a substantive political agenda with legislators based on their common social and political background, a reality that in any event had begun to dissipate in the eighteenth century with the increasing representation of commercial classes in Parliament. Nor is it the point that judges could sometimes claim a privileged knowledge of the legislature’s specific substantive intent, based on participation in drafting legislation. The more fundamental point is that the shared institutional background of judges and lawyer-trained legislators derived from their membership and training in the Inns of Court and, in many instances, service as both judges and members of Parliament — had the effect of increasing the judge’s sense of institutional competence in working out the law, regardless of substantive impact. Judges simply thought of themselves as politically savvy.
Sir William Blackstone said in his Commentaries on the Laws of England, was to explain the decisions preserved in the record of the court. He indeed neatly described the whole system:
And thus much for the first ground and chief corner stone of the laws of England, which is, general immemorial custom or common law, from time to time declared in the decisions of the courts of justice; which decisions are preserved among our public records, explained in our reports, and digested for general use in the authoritative writings of the venerable sages of the law. 
Connotations to Term (Common Law)
The common law forms a major part of the law of those countries of the world with a history as British territories or colonies. It is notable for its inclusion of extensive non-statutory law reflecting precedent derived from centuries of judgments by working jurists. There are three important connotations to the term. (Wikipedia)
One is used to distinguish the authority that promulgated a particular proposition of law: for example, the United States typically has “statutes” enacted by a legislature, “regulations” promulgated by executive branch agencies pursuant to a delegation of rule-making authority from a legislature, and “common law” decisions issued by courts (or quasi-judicial tribunals within agencies) that discuss and decide the fine distinctions in statutes and regulations. See statutory law and non-statutory law. (Wikipedia)
The second distinguishes “common law” jurisdictions (most of which descend from the English legal system) that place great weight on such common law decisons, from “civil law” or “code” jurisdictions (many of which descend from the Napoleonic code in which the weight accorded judicial precedent is much less. (Wikipedia)
The third distinguishes “common law” (or just “law”) from “equity”. Until the beginning of the 20th Century, most common law jurisdictions had two parallel court systems, courts of “law” that could only award money damages and recognised only the legal owner of property, and courts of “equity” that recognised trusts of property and could issue injunctions, orders to do or stop doing something. Although the separate courts were merged long ago in most jurisdictions, or at least all courts were permitted to apply both law and equity, the distinction between law and equity remains important in (a) categorising and prioritising rights to property, (b) determining whether the Seventh Amendment’s guarantee of a jury trial applies (a determination of a fact necessary to resolution of a “law” claim) or whether the issue can only be decided by a judge (issues of equity), and (c) in the principles that apply to the grant of equitable remedies by the courts. (Wikipedia)
Theories of Legal Science
Theories of legal science could be developed in various ways, but the central idea was that the law which the courts — if we really believe in the rule of law — apply in the resolution of disputes is derivative of certain basic or fundamental legal principles, and the expertise of the professional lawyer consists in his knowledge and understanding of these principles, and his skill in working out how they should properly be applied to the complexities of life. These principles underlie the practice of the courts in much the same way as the principles of language underlie the process of human communication, and only experts can identify and formulate them correctly. The theory provided a clear programme for legal education, set out in lyrical prose in 1892 by Professor the Honourable Edward J. Phelps of the Yale law School, now a somewhat forgotten figure, but in his day by no means negligible: The very first and indispensable requisite in legal education . . . is the acquisition of a clear and accurate perception, a complete knowledge, a strong and tenacious grasp of those unchangeable principles of the common law which underlie and permeate its whole structure, and which control all its details, its consequences, its applications to human affairs. 
The ambiguity of the evidence about the judicial role is consistent with the historical reality that the constitution-builders were intensely pragmatic, not concerned with whether the governments they created fit some theoretically consistent mold. Indeed, the need to attract widespread support led them to compromises that avoided a rigid constitutional model. They rejected the extremes of monarchical and legislative sovereignty, but they were never entirely clear what they created in between. All that was clear was that the boundaries, within which judges operated, as determined by the reality of popular sovereignty and legislative competence, were narrower than those set by the formal principle of parliamentary sovereignty in England.
The ambivalence and controversy about judging also are apparent in what little evidence we have from judicial practice during the 1776-89 period. Statutes were extended and limited; extension included adding to statutory lists and the liberal interpretation of statutes dealing with selected subject matter. Limitation of statutes included both restraining coverage suggested by overly broad texts to help the legislature achieve an imperfectly thought-out scheme and the narrow interpretation of statutes in derogation of the common law or common right, which sometimes did and did not implement likely legislative intent. Courts did these things both to prevent absurdity and injustice (fundamental values) and to avoid inconvenient results. Even statutes and common law were not so clearly differentiated; both were conceived of as evidence of a broader legal landscape. During all of these changes, judges acted more or less unself-consciously in performing their judicial role.
Today, and indeed for many centuries, the common law system has been the product of a prolonged exercise in casuistry, an activity more generally associated with moral reasoning. The judges, by deciding particular cases presented to them in litigation, respecting the claims, often conflicting, of consistency and rationality, have provided the raw materials from which has been built up a system of law. This system, the common law, evolved out of the traditional practices followed in the Royal Courts in resolving disputes. One way in which we can view the common law, conceived as a complex body of abstract doctrine, is as a way of thinking about, of conceptualizing, or rationalizing what has traditionally been done. Courts decide those few disputes which cannot otherwise be settled, and the notion of a decision is everywhere problematic. Anyone who has worked, for example, in a large organization will be familiar with the problem of discovering who actually takes the decisions, and why, and when, and where, and with the fact that they themselves never seem to be involved. It is hardly surprising that the relationship between judicial decisions, free will, and abstract legal doctrine, has long been a subject of a theoretical dispute which shows no sign of ending. 
ConclusionA comparative institutional perspective also goes a long way toward defusing the objections to the role of staff in writing legislative history. The legitimacy argument emphasizes that staff are unelected and that “routine deference to the detail of committee reports, and the predictable expansion in that detail which routine deference has produced, are converting a system of judicial construction into a system of committee staff prescription.” (Jordan, 1988)
But objections to staff-written legislative history do not add much to the objections to legislative history from committee sources. The fact is that statutes are also a committee-staff product. Committees operate as minibureaucracies that require staff to play a significant role.
They are similar to agency regulations, although they lack the procedural advantages provided by public notice and comment. Competence analysis of judicial use of legislative history also provides a good way for courts to decide whether to defer to agency rules or to legislative history. From a perspective of competence, agency rules are often preferable, having gone through a process in which the public receives notice and an opportunity to he heard. Legitimacy analysis, if it successfully equates legislative history with legislative intent, threatens to shunt an agency rule aside as weaker evidence of what the legislature wanted.
In sum, legislative history has political uses as well as abuses, and efforts to delegitimatize judicial reliance on legislative history result from the same kind of exaggeration that affects most debates over the judicial role in statutory interpretation. Some legislative history is competent and some is not. Judges will not always get it right, but that is no truer of legislative history than other criteria of statutory meaning, such as text, purpose, and background considerations.
A. W. Brian Simpson. Leading Cases in the Common Law. Oxford University Press, 1996
AUSTIN J., Lectures on Jurisprudence or the Philosophy of Positive Law (London, 1920)
Blackstone, Commentaries on the Laws of England (London, 1765-9), i.73
Common Law – ENCYCLOPEDIA – The History Channel UK
http://www.thehistorychannel.co.uk/site/search/search.php?word=commonla Accessed October 12, 2006
Common law – Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Common_law Accessed October 12, 2006
Cynthia Jordan, “‘Old Words’ in ‘New Circumstances’: Language and Leadership in PostRevolutionary America,” 40 American Quarterly491 (1988)
James Barry, “The Council of Revision and the Limits of Judicial Power,” 56 U. Chi. L. Rev.235 (1989)
 AUSTIN J., Lectures on Jurisprudence or the Philosophy of Positive Law ( London, 1920) Blackstone, Commentaries on the Laws of England (London, 1765-9), i.73
 A. W. Brian Simpson. Leading Cases in the Common Law. Oxford University Press, 1996
 A. W. Brian Simpson. Leading Cases in the Common Law. Oxford University Press, 1996