In common law legal systems, the law is created and/or refined by judges: a decision in the case currently pending depends on decisions in previous cases and affects the law to be applied in future cases. When there is no authoritative statement of the law, common law judges have the authority and duty to "make" law by creating precedent.
The body of precedent is called "common law" and it binds future decisions. In future cases, when parties disagree on what the law is, an "ideal" common law court looks to past precedential decisions of relevant courts. If a similar dispute has been resolved in the past, the court is bound to follow the reasoning used in the prior decision (this principle is known as stare decisis). If, however, the court finds that the current dispute is fundamentally distinct from all previous cases, it will decide as a "matter of first impression." Thereafter, the new decision becomes precedent, and will bind future courts under the principle of stare decisis.
In practice, common law systems are considerably more complicated than the "ideal" system described above. The decisions of a court are binding only in a particular jurisdiction, and even within a given jurisdiction, some courts have more power than others. For example, in most jurisdictions, decisions by appellate courts are binding on lower courts in the same jurisdiction and on future decisions of the same appellate court, but decisions of non-appellate courts are only non-binding persuasive authority. Interactions between constitutional law, common law, statutory law and regulatory law also give rise to considerable complexity. However stare decisis, the principle that similar cases should be decided according to similar rules, lies at the heart of all common law systems.
Common law legal systems are in widespread use, particularly in those nations which trace their legal heritage to Britain, including the United Kingdom, the United States, most of Canada, and other former colonies of the British Empire.
The science of the Law comes showing an increasing interest for the paper that the previous judicial decisions have in the solution of future cases. So much it is so, in the area of the European systems of the codified Law, we have happened of speaking about the "jurisprudence" of the organs of cassation to the "precedents"; of positions as "the jurisprudence is not a source of the Law" to "it is necessary to bear in mind the judicial precedents ", recognizing them, thus, a certain juridical relevancy in order to orientate on the resolution of his concrete case in view of previous judgments, specially those of the same court.
With the above mentioned end this site, that is to say, of facilitating and giving when the judicial precedents selected by attorneys to know specialists, who would be of bearing in mind to foresee the resolution of YOUR CONCRETE CASE in Spain.