Posek

Posek ( , pl. Poskim,  ) is the term in  Jewish law for a "decisor" — a legal scholar who determines the position of Halakha in cases of law where previous authorities are inconclusive, or in those situations where no clear halakhic precedent exists.

The decision of a posek is known as a psak din or psak halakha ("ruling of law"; pl. piskei din, piskei halakha) or simply a "psak". In Hebrew, פסק is the root implying to "stop" or "cease"—the posek brings the process of legal debate to finality. Piskei din are generally recorded in the responsa literature.

Formulating a ruling (psak din) 
In formulating a ruling, a posek will base the psak din on a careful analysis of the relevant underlying legal principles, as well as a careful study of the application of these principles. A Posek must therefore be thoroughly versed in rabbinic literature, from the Babylonian Talmud, through the major medieval codifications of the Law and up to recent decisions.

The process of analysis usually entails:
 an initial study of the relevant Talmudic Sugyas with commentaries;
 tracing the development of all related material in the Rishonim (Medieval rabbinic authorities prior to the Shulkhan Aruch) through the Arba'ah Turim and Shulkhan Arukh;
 and finally, a close analysis of the works of the Acharonim (rabbinic authorities from about the 16th century onwards) discussing the halakha as recorded in the literature of the Rishonim (and earlier Acharonim).

The ruling itself is an attempt to apply the precedents and principles of the Tradition to the question being asked. One common goal of poskim in this regard is, as far as possible, to be consistent with the codified law, as well as with the maximal relevant legal precedents, generally being decisions recorded in the responsa literature.

The role of the Posek

Orthodox Judaism 
Poskim play an integral role in Orthodox Judaism in general and Haredi Judaism in particular. 
 In the Haredi world, each community will regard one of its poskim as its Posek HaDor ("Posek of the present Generation").
 Hasidic Jews rely on the Rov in their community (sometimes but not always Rebbes also get the position as Rov) or leading posek recommended by their Rebbe. Yet there are some Jews who are Hasidic but are not part of a specific movement. These hassidim will vary in who they follow sometimes following generic hassid-style poskim like Rav Shmuel Wosner. 
 Modern Orthodox Jews may select a posek on a more individual rather than a communal basis, although customs vary.
The approach taken here will, generally, be as above. Thus poskim will 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 
Conservative Judaism approaches the idea of Posek, and Halakha in general, somewhat differently, and 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; see Conservative Halakha. Although there are some "poskim" in the Conservative movement - e.g. Rabbis 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 as mara d'atra to interpret Jewish law for his own community, regardless of the responsa of the Law Committee.

Progressive Judaism 
Both Reform and Reconstructionist Judaism do not regard the halakha as binding.

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. 

The Reconstructionist position is that if Jews would have formed cohesive communities again, their rulings would be binding, yet 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.

List of poskim and major works

Poskim of past years

Pre-20th century 
 Yoel Sirkis (1561–1640, Bach)
 Sabbatai ha-Kohen (1621–1662, Shach)
 David HaLevi Segal (1586–1667, Turei Zahav)
 Avraham Gombiner (c.1633–c.1683, Magen Avraham)
 Yechezkel Landau (1713–1793, Noda bi-Yehudah)
 Vilna Gaon (1720–1797, Gra)
 Shneur Zalman of Liadi (1745–1812, Shulchan Aruch ha-Rav)
 Avraham Danzig (1748–1820, Chayei Adam)
 Moses Sofer (1762–1839, Chasam Sofer)
 Menachem Mendel Schneersohn (1789–1866, Tzemach Tzedek)
 Shlomo Ganzfried (1804–1886, Kitzur Shulchan Aruch)
 Yitzchak Elchanan Spektor (1817–1896)

Orthodox 
 Yechiel Michel Epstein (1829–1907, Aruch ha-Shulchan)
 Yoseph Chaim of Bagdad (1832–1909, Ben Ish Chai, Rav Pealim)
 Moshe Greenwald (1853–1910, Arugath Habosem)
 Eliezer David Greenwald (1867–1928, Keren L'Dovid)
 Yisrael Meir Kagan (1838–1933, Mishnah Berurah, Chafetz Chaim)
 Abraham Isaac Kook (1865–1935)
 Yaakov Chaim Sofer (1870–1939, Kaf ha-Chaim)
 Chaim Ozer Grodzinski (1863–1940, Achiezer)
 Avraham Duber Kahana Shapiro (1870–1943)
 Avraham Yeshayahu Karelitz (1878–1953, Chazon Ish)
 Avraham Chaim Naeh (1890–1954 Ketzos ha-Shulchan, Shiurei Mikveh, Shiurei Torah)
 Yonasan Steif, (1877–1958)
 Aharon Kotler (1892–1962)
 Yechiel Yaakov Weinberg (1878–1966, Seridei Eish)
 Eliezer Silver (1882–1968)
 Yosef Eliyahu Henkin (1881–1973) 
 Yehezkel Abramsky (1886–1976)
 Yoel Teitelbaum (1887–1979, Vayoel Moshe, Divrei Yoel)
 Yitzchok Hutner (1906–1980)
 Zvi Yehuda Kook (1891–1982)
 Yosef Greenwald (1903–1984, Vayaan Yosef)
 Yaakov Kamenetsky (1891–1986)
 Moshe Feinstein (1895–1986, Iggerot Moshe)
 Yitzchok Yaakov Weiss (1902–1989, Minchas Yitzchak)
 Joseph B. Soloveitchik (1903–1993)
 Shlomo Goren (1918–1994)
 Shlomo Zalman Auerbach (1910–1995, Minchat Shlomo)
 Pinhas Hirschprung (1912–1998)
 Hayim David HaLevi (1924–1998), Chief Rabbi of Tel Aviv, author of the set of halakha Mekor Hayim
 Chanoch Dov Padwa (1908–2000, Cheishev Ho'ephod)
 Chaim Kreiswirth (1918–2001)
 Ephraim Oshry (1914–2003)
 Baruch Ben Haim (1921–2005)
 Eliezer Waldenberg (1917–2006, Tzitz Eliezer)
 Avraham Shapira (c. 1914–2007)
 Yaakov Yitzhak Neumann (1920–2007, Ogiro Be'Oholcho)
 Meir Brandsdorfer (Kaneh Bosem) (1934–2009)
 Mordechai Eliyahu (1929–2010)
 Menashe Klein, (1924–2011, Ungvar Rav, Mishneh Halachos)
 Chaim Pinchas Scheinberg (1910–2012)
 Yosef Shalom Eliashiv (1910–2012)
 Ovadia Yosef (1920–2013, Yabbia Omer)
 Yisroel Belsky (1938–2016)
 Shmuel Wosner (Shevet HaLevi) (1913–2015)
 Aaron Lichtenstein (1933–2015), rosh yeshiva of Yeshivat Har Etzion
 Aharon Leib Shteinman (c. 1913–2017)
 Fishel Hershkowitz, Klausenburger dayan in Williamsburg, Brooklyn, New York (1922–2017)
 Nissim Karelitz (1926-2019)

Conservative and Reform 
 Jacob Zallel Lauterbach (1873–1942)
 Louis Ginzberg (1873–1953, The Responsa of Professor Louis Ginzberg)
 Isaac Klein (1905–1979, A Guide to Jewish Religious Practice)
 Jacob Agus (1911–1986, Dialogue and Tradition)
 Solomon Freehof (1892–1990, Reform Jewish Practice and its Rabbinic Background)

Living poskim

 Shmuel Kamenetsky, rosh yeshiva, Talmudical Yeshiva of Philadelphia (1924- )
 Gedalia Dov Schwartz, av beit din of Beth Din of America and the Chicago Rabbinical Council (1925- )
 Chaim Kanievsky (1928- )
 Nahum Rabinovitch, rosh yeshiva of Yeshivat Birkat Moshe (1928- )
 Dovid Feinstein, rosh yeshiva at Mesivtha Tifereth Jerusalem (1929- )
 Zalman Nechemia Goldberg, av beit din, rosh yeshiva of Machon Lev, editor-in-chief of the Encyclopedia Talmudit (1932- )
 Haim Drukman (1932- )
 Yitzchak Abadi (1933- )
 Dov Lior (1933- )
 Avigdor Nebenzahl (1935- )
 Zephaniah Drori (1937- )
 Yaakov Ariel (1937- )
 Zalman Baruch Melamed (1937- )
 Yisrael Ariel (1939- )
 Eliyahu Ben Haim (1940- )
 Hershel Schachter, rosh yeshiva at RIETS (1941- )
 Shlomo Aviner (1943- )
 Yehuda Henkin (1945- )
 Mordechai Willig, rosh yeshiva at RIETS (1947- )
 Yitzhak Yosef, Chief Sephardic Rabbi of the State of Israel, author of the set Yalkut Yosef (1952- )
 Osher Weiss (Minchas Osher) (1953- )
 Yitzchak Berkovits, rosh kollel The Jerusalem Kollel (1953- )
 Eliezer Melamed (1961- )
 Simcha Bunim Cohen, prolific author and pulpit rabbi in Lakewood, New Jersey
 Pinchas Toledano, hakham of the Spanish and Portuguese Jews of the Netherlands
 Ephraim Padwa rabbi of Union of Orthodox Hebrew Congregations
 Gavriel Zinner author of the Nitei Gavriel series on halakha
 Yechezkel Roth Karlsburger Rav, author of Emek HaTeshuvah
 Yisroel Dovid Harfenes author of Yisroel Vehazmanim, Mekadesh Yisroel and Nishmas Shabos

See also 
 Dayan (rabbinic judge)
 Gemara
 History of responsa in Judaism
 Oral Torah

References

Further reading 
 N. S. Hecht et al., An Introduction to the History and Sources of Jewish Law, Oxford University Press.
 Louis Jacobs, A Tree of Life: Diversity, Creativity, and Flexibility in Jewish Law, second edition, Littman Library of Jewish Civilization, 1999.
 Mendell Lewittes, Jewish Law: An Introduction, Jason Aronson Inc., 1994.
 , archived from the 2004 original at nishmat.net 
 An introduction to the system of Jewish Law, aish.com
 Jewish Law Research Guide, University of Miami Law Library
 Jewish Law: Examining Halacha, Jewish Issues and Secular Law (online journal)
 AskMoses.com, Live Answers

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