The decision of a posek is known as a psak halakha ("ruling of law"; pl. piskei halakha) or simply a "psak". Piskei halakha are generally recorded in the responsa literature.
Generally, each community will regard one of its poskim as its Posek HaDor ("posek of the present generation").
Most rely on the rav in their community (in Hasidic communities, sometimes the rebbe) or the leading posek.
Poskim will generally not overrule a specific law unless based on an earlier authority: a posek will generally extend a law to new situations but will not change the Halakhah; see the article on Orthodox Judaism.
Conservative Judaism approaches the idea of posek, and Halakha in general, somewhat differently: poskim here apply a relatively lower weighting to precedent, and will thus frequently re-interpret (or even change) a previous ruling through a formal argument. Although there are some poskim in the Conservative movement (e.g., Louis Ginzberg, David Golinkin, Joel Roth, and Elliot Dorff), the rulings of any one individual rabbi are considered less authoritative than a consensus ruling. Thus, the Conservative movement's Rabbinical Assembly maintains a Committee on Jewish Law and Standards, whose decisions are accepted as authoritative within the American Conservative movement. At the same time, every Conservative rabbi has the right of mara d'atra to interpret Jewish law for his, her, or their own community regardless of the responsa of the Law Committee.
Although Reform stresses the individual autonomy of its membership, it never completely abandoned the field of responsa literature, if only to counter its rivals' demands. Even Classical Reformers such as Rabbi David Einhorn composed some. Rabbi Solomon Freehof, and his successor Rabbi Walter Jacob, attempted to create a concept of "Progressive Halacha", authoring numerous responsa based on a methodology laying great emphasis on current sensibilities and ethical ideals. Full text collections of Reform responsa are available on the website of the Central Conference of American Rabbis.[1][2]
The Reconstructionist position is that if Jews had formed cohesive communities again, their rulings would be binding, but presently Judaism is in a "post-Halakhic state". Therefore, their basic policy is to allow tradition "a vote, not a veto" in communal and personal affairs.[3]
In chronological order, by the year of birth, and if needed, secondarily, by year of death and surname.
Poskim of past years
Toledot HaPoskim, History of the Jewish Codes, by Chaim Tchernowitz.
Meyer, Michael A. (1993). "Changing Attitudes of Liberal Judaism toward Halakhah and Minhag". Proceedings of the World Congress of Jewish Studies. JSTOR23536120. See a collection of CCAR Responsa.
Sacks, Jonathan (1992). Crisis and Covenant: Jewish Thought After the Holocaust. Manchester University Press. p.158. ISBN0-7190-4203-8.
Hecht, N. S.; etal. (eds.). An Introduction to the History and Sources of Jewish Law. Oxford University Press. ISBN0-19-826262-0.
Jacobs, Louis (1999). A Tree of Life: Diversity, Creativity, and Flexibility in Jewish Law. Littman Library of Jewish Civilization (Seconded.). ISBN1-874774-48-X.
Lewittes, Mendell (1994). Jewish Law: An Introduction. Jason Aronson. ISBN1-56821-302-6.