Posek (Hebrew פוסק; pl. Poskim) is the term in Jewish law for "legal decisor" - a rabbi who decides the Halakha in cases of law where previous authorities are inconclusive. This decision 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 - here the posek brings the process of legal debate to finality. Piskei Din are generally recorded in the responsa literature.

The Posek will base his psak din on a study of relevant precedents in light of a careful analysis of the underlying legal principles. The Posek will have studied the application of the halakha through consideration of all relevant legal precedents as recorded in the responsa literature. He will have mastered the underlying principles in that area through study of the relevant Talmudic tractates with commentaries. This analysis will include tracing the development of the corresponding legal material in the Rishonim through the Shulkhan Arukh, and finally the Acharonic material on the halakha as recorded in that work. It is clear that a Posek will be thoroughly versed in Rabbinic literature and must be a master Talmudist.

In Orthodox Judaism poskim will not overrule a specific law, unless based on an earlier authority; the posek will generally extend the law to new situations, but will not, as such, change the Halakha. (For example, some Halakhic rulings related to electricity when it was new, were derived from rulings concerning another form of human-managed energy, fire).

Conservative Judaism and Masorti Judaism may re-interpret or even change a law through a formal argument. Here though, the role of poskim is less prominent. The rulings of any one individual are considered less binding than a consensus ruling. The Conservative movement's Rabbinical Assembly maintains a Committee on Jewish Law and Standards, whose decisions are accepted as authoritative.

Poskim are not found in Reform Judaism and Reconstructionist Judaism, as these denominations do not hold that Jewish law is normative (i.e. accepted as binding.)

Rabbinic education will correspond to the approach to Piskei Din as described above. In Orthodox Judaism, semicha requires an arduous learning program in the codes of Jewish law and responsa. Conservative Judaism has less stringent study requirements for Talmud and responsa study. In Reconstructionist and Reform Judaism emphasis is not placed on the study of normative Jewish law.

See also

• The Halakhic process
• How Halakha is viewed today
• The Talmud in modern-day Judaism
• Oral law
• Gemara
• Eras of history in Jewish law
• Codes of Jewish law
• List of rabbis

References

• 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 1999, Littman Library of Jewish Civilization.
• Mendell Lewittes Jewish Law: An Introduction, Jason Aronson Inc.
• Authority and Autonomy in Pesikat HaHalacha, nishmat.net
• An introduction to the system of Jewish Law, aish.com
• Jewish Law Research Guide, University of Miami Law Library