Comparative law is the study of differences and similarities between the law of different countries. More specifically, it involves study of the different legal systems in existence in the world, including the common law, the civil law, socialist law, Islamic law, Hindu law, and Chinese law. It includes the description and analysis of foreign legal systems, even where no explicit comparison is undertaken. The importance of comparative law has increased enormously in the present age of internationalism, economic globalization and democratization.
The birth of modern comparative law is generally attributed to Europe in the eighteenth century. However, prior to that, legal scholars (forerunners of today's comparativists and international lawyers) practiced comparative method. In Russian legal history, for instance, comparative method dates back to the sixteenth century.
According to the prevalent view, Montesquieu is regarded as the 'father' of comparative law. His comparative approach is obvious in the following excerpt from Chapter III of Book I of what many consider to be his masterpiece, De l'esprit des lois:
[The political and civil laws of each nation] should be adapted in such a manner to the people for whom they are framed that it should be a great chance if those of one nation suit another. They should be in relation to the nature and principle of each government; whether they form it, as may be said of politic laws; or whether they support it, as in the case of civil institutions. They should be in relation to the climate of each country, to the quality of its soil, to its situation and extent, to the principal occupation of the natives, whether husbandmen, huntsmen, or shepherds: they should have relation to the degree of liberty which the constitution will bear; to the religion of the inhabitants, to their inclinations, riches, numbers, commerce, manners, and customs.
Also, in Chapter XI (entitled 'How to compare two different Systems of Laws') of Book XXIX he advises that "to determine which of those systems [i.e. the French and English systems for the punishment of false witnesses] is most agreeable to reason, we must take them each as a whole and compare them in their entirety." Yet another excerpt where Montesqieu's comparative approach is evident is the following one from Chapter XIII of Book XXIX:
As the civil laws depend on the political institutions, because they are made for the same society, whenever there is a design of adopting the civil law of another nation, it would be proper to examine beforehand whether they have both the same institutions and the same political law.
Birth as a discipline in the U.S. 
Comparative law in the US was brought by a legal scholar fleeing persecution in Germany, Rudolf Schlesinger. Schlesinger eventually became professor of comparative law at Cornell Law School helping to spread the discipline throughout the US.
Comparative law is an academic study of separate legal systems, each one analysed in its constitutive elements; how they differ in the different legal systems, and how their elements combine into a system.
Several disciplines have developed as separate branches of comparative law, including comparative constitutional law, comparative administrative law, comparative civil law (in the sense of the law of torts, delicts, contracts and obligations), comparative commercial law (in the sense of business organisations and trade), and comparative criminal law. Studies of these specific areas may be viewed as micro- or macro-comparative legal analysis, i.e. detailed comparisons of two countries, or broad-ranging studies of several countries. Comparative civil law studies, for instance, show how the law of private relations is organised, interpreted and used in different systems or countries. It appears today the principal purposes of comparative law are:
- to attain a deeper knowledge of the legal systems in effect
- to perfect the legal systems in effect
- possibly, to contribute to a unification of legal systems, of a smaller or larger scale (cf. for instance, the UNIDROIT initiative)
Comparative law is a very important discipline in communication between legal systems. It may provide the basis for the production of bilingual dictionaries that include the information necessary to make legal communication across borders successful. It also helps mutual understanding and the dispelling of prejudice and misinterpretation. In this globalising world, comparative law is important for it provides a platform for intellectual exchange in terms of law and it cultivates a culture of understanding in a diverse world. Furthermore, comparative law helps in broadening horizons for law reformers and legislators around the world. It can also be helpful in international relations in shaping foreign policies.
Relationship with other legal subjects 
Comparative law is different from the fields of general jurisprudence (legal theory), international law, including both public international law and private international law (also known as conflict of laws).
Despite the differences between comparative law and these other legal fields, comparative law helps inform all of these areas of normativity. For example, comparative law can help international legal institutions, such as those of the United Nations System, in analyzing the laws of different countries regarding their treaty obligations. Comparative law would be applicable to private international law when developing an approach to interpretation in a conflicts analysis. Comparative law may contribute to legal theory by creating categories and concepts of general application. Comparative law may also provide insights into the question of legal transplants, i.e. the transplanting of law and legal institutions from one system to another. The notion of legal transplants was coined by Alan Watson, one of the world's renowned legal scholars specializing in comparative law.
Also, the usefulness of comparative law for sociology of law (and vice versa) is very large. The comparative study of the various legal systems may show how different legal regulations for the same problem function in practice. Conversely, sociology of law may help comparative law answer questions, such as: How do regulations in different legal systems really function in the respective societies? Are certain legal rules comparable? How do the similarities and differences between legal systems get explained?
Classifications of legal systems 
Arminjon, Nolde, and Wolff 
Arminjon, Nolde, and Wolff believed that, for purposes of classifying the (then) contemporary legal systems of the world, it was required that those systems per se get studied, irrespective of external factors, such as geographical ones. They proposed the classification of legal system into seven groups, or so-called 'families', in particular the
- French group, under which they also included the countries that codified their law either in 19th or in the first half of the 20th century, using the Napoleonic code civil of year 1804 as a model; this includes countries and jurisdictions such as Italy, Portugal, Spain, Louisiana, states of South America (such as Brazil), Quebec, Santa Lucia, Romania, the Ionian Islands, Egypt, and Lebanon
- German group
- Scandinavian group (comprising the laws of Denmark, Norway, Sweden, Finland, and Iceland)
- English group (incl. England, the United States, Canada, Australia and New Zealand inter alia)
- Russian group
- Islamic group (used in the Muslim world)
- Hindu group
David proposed the classification of legal systems, according to the different ideology inspiring each one, into five groups or families:
- Western Laws, a group subdivided into the:
- Soviet Law
- Muslim Law
- Hindu Law
- Chinese Law
Especially with respect to the aggregating by David of the Romano-Germanic and Anglo-Saxon Laws into a single family, David argued that the antithesis between the Anglo-Saxon Laws and Romano-German Laws, is of a technical rather than of an ideological nature. Of a different kind is, for instance, the antithesis between (say) the Italian and the American Law, and of a different kind that between the Soviet, Muslim, Hindu, or Chinese Law. According to David, the Romano-Germanic legal systems included those countries where legal science was formulated according to Roman Law, whereas common law countries are those where law was created from the judges. The characteristics that he believed uniquely differentiate the Western legal family from the other four are
- liberal democracy
- capitalist economy
- Christian religion
Zweigert and Kötz 
Zweigert and Kötz propose a different, multidimensional methodology for categorizing laws, i.e. for ordering families of laws. They maintain that, to determine such families, five criteria should be taken into account, in particular: the historical background, the characteristic way of thought, the different institutions, the recognized sources of law, and the dominant ideology. Using the aforementioned criteria, they classify the legal systems of the world into six families:
- Roman family
- German family
- Common law family
- Nordic family
- Family of the laws of the Far East (China and Japan)
- Religious family (Muslim and Hindu law)
Professional associations 
See also 
- Legal systems of the world (includes links to legal systems of specific countries)
- Comparative law wiki, online wikis where jurists can complete questionnaires regarding their home legal system;
- Sir Henry Maine
- Friedrich Karl von Savigny
- German Historical School
- Comparative criminal justice
- Rule of law
- Rule According to Higher Law
- Sociology of law
- Annual Bulletin of the Comparative Law Bureau (1908), the first comparative law journal in the U.S
- Butler, William E. (2009). Russia and the Law of Nations in Historical Perspectives: Collected Essays. London: Wildy, Simmonds. p. 124. ISBN 1-884445-42-X.
- Charles de Secondat, Baron de Montesquieu, The Spirit of Laws, Translated by Thomas Nugent, revised by J. V. Prichard, Based on a public domain edition published in 1914 by G. Bell & Sons, Ltd., London
- Traité de droit comparé - in French; Paris 1950-1952
- Traité élémentaire de droit civile comparé: Introduction à l'étude des droits étrangers et à la méthode comparative - in French; Paris, 1950
- An Introduction to Comparative Law, translation from the Germany original: T. Weir, 3rd edition; Oxford, 1998
- MS MacDougal, ‘The Comaprative Study of Law for Policy Purposes: Value Clarification as an Instrument of Democratic World Order’ (1952) 61 Yale Law Journal 915, on the difficulties and requirements of good comparative law.
- Cotterrell, Roger (2006) Law, Culture and Society: Legal Ideas in the Mirror of Social Theory. Aldershot: Ashgate.
- David, René; Brierley, John E. C. (1985). Major Legal Systems in the World Today: An Introduction to the Comparative Study of Law. London: Stevens. ISBN 0-420-47340-8.
- De Cruz, Peter (2007) Comparative Law in a Changing World, 3rd edn (1st edn 1995). London: Routledge-Cavendish.
- Donahue, Charles (2008) 'Comparative Law before the Code Napoléon' in Reimann, Mathias and Zimmermann, Reinhard (eds.) The Oxford Handbook of Comparative Law. Oxford: Oxford University Press.
- Glanert, Simone (2008) 'Speaking Language to Law: The Case of Europe', Legal Studies 28: 161–171.
- Glenn, H. Patrick (2010) Legal Traditions of the World, 4th edn (1st edn 2000). Oxford: Oxford University Press.
- Legrand, Pierre (1996) 'European Legal Systems Are Not Converging', International and Comparative Law Quarterly 45: 52 - 81.
- Legrand, Pierre (1997) 'Against a European Civil Code', Modern Law Review 60: 44 - 63.
- Legrand, Pierre and Munday, Roderick (2003) (eds.) Comparative Legal Studies: Traditions and Transitions. Cambridge: Cambridge University Press.
- Legrand, Pierre (2003) 'The Same and the Different' in Legrand, Pierre and Munday, Roderick (eds.) Comparative Legal Studies: Traditions and Transitions. Cambridge: Cambridge University Press.
- Mattei, Ugo; Ruskola, Teemu (2009). Schlesinger's Comparative Law. London: Foundation. ISBN 1-58778-591-9.
- Menski, Werner (2006) Comparative Law in a Global Context: the Legal Traditions of Asia and Africa. Cambridge: Cambridge University Press.
- Nelken, David (2000) (ed.) Contrasting Criminal Justice: Getting from Here to There. Aldershot: Ashgate/Dartmouth.
- Orucu, Esin and Nelken, David (2007) (eds.) Comparative Law: A Handbook. Oxford: Hart.
- Reimann, Mathias and Zimmermann, Reinhard (2008) (eds.) The Oxford Handbook of Comparative Law. Oxford: Oxford University Press.
- Alan Watson Foundation
- Australian Institute of Comparative Legal Systems
- Eason Weinmann Center for Comparative Law at Tulane University Law School
- International Academy of Comparative Law French
- International Association of Constitutional Law
- International Constitutional Law
- Max Planck Institute for Comparative Public Law and International Law
- Oxford University Comparative Law Forum