A shomer Shabbat or shomer Shabbos (plural shomré Shabbat or shomrei Shabbos; Hebrew: שומר שבת) is a person who observes the mitzvot (commandments) associated with Judaism's Shabbat ("Sabbath", dusk on Friday until sunset, Saturday.)
In particular, under Jewish law (halakhah), the person who is Shomer Shabbat is expected to conform to the prohibitions against certain forms of melacha - creative acts. The observant Jew does not cook, spend money, write, operate electrical devices, or do other activities prohibited on Shabbat. In addition, a variety of positive Sabbath commandments are expected to be fulfilled, such as Sabbath meals, rituals, prayers, kindness, benignity and rest.
In contemporary Orthodox Judaism, the shomer Shabbat would typically strive to follow all the rules associated with the Sabbath. Within the liberal movements of Judaism, the phrase may signify a person who takes seriously the observance of the core mitzvot.
The shomer Shabbat is an archetype mentioned in Jewish songs (e.g., Baruch El Elyon) and the intended audience for various treatises on Jewish law and practice for the Sabbath day (e.g., Shmirat Shabbat ke-Hilkhata). In 2000, the media took note that the candidate for U.S. Vice President, Senator Joseph Lieberman, is a shomer shabbat.
Origin and usage 
The term shomer Shabbat is derived from the wording of one of the Ten Commandments in Deuteronomy (5:14-15), which instructs the Hebrews to "observe" the Sabbath day and sanctify it. One must eat without cooking it on the Sabbath and get to shul without turning the car on. (In Exodus, the Decalogue states that they should "remember" the Sabbath.) The term appears in the Hebrew Bible only in Isaiah 56:2,6. Shomer Shabbat is not used in the Mishnah or Talmud, it occurs a handful of times in the midrashic literature. Similarly, the term is used infrequently in medieval and early modern rabbinic literature: for example, once in Maimonides, never in the Shulchan Aruch and rarely in responsa prior to the 20th century. The term has been used frequently, though, during the last 100 years. It is also used to name shuls, such as a predecessor to Machzike Hadath in London, a Gateshead synagogue (founded in 1897), and one in Boro Park.
Over the years, shomer Shabbat readers have been offered specialized manuals on halakhah, including a popular book by Rabbi Yehoshua Neuwirth and Sefer Shomer Shabbat by David ben Aryeh Leib of Lida (ca. 1650-1696), pictured.
Social dimensions 
In the past, it was relatively uncommon to be shomer Shabbat in the United States, even among the Orthodox. Emanuel Feldman writes that it was a “rarity” in the American Orthodoxy of the 1950s. Overall, political scientist Charles Liebman estimated that about 4% of American Jews were shomer shabbos in the 1960s. Among other factors, Saturday had not yet been established as a day off from work, and many American Jews found that insistence on Shabbat observance would cost them their livelihood. During this period, to improve observance, Flatbush rabbis operated a Shomer Shabbat council and ran a Shomer Shabbat parade.
According to the National Jewish Population Survey (2000–2001), about 50% of affiliated Jews (versus 8% of unaffiliated) light Sabbath candles. The first mitzvah in shomer Shabbat home each Friday evening, candle-lighting is performed by 85% of Orthodox, 50% of Conservative and 25% of Reform Jews (Ament 2005:31). In total, Sabbath candle-lighting is practiced by 28% of NJPS survey respondents representative of 4.3 million Jews (United Jewish Communities 2003:7).
With the increasing observance among Orthodox Jews, the status of shomer Shabbat has become more important. For example, one of the key questions asked about Orthodox Jewish day schools is whether it allows children who are not shomer Shabbat. The shomer shabbat distinction has been found to be a factor in the social integration of children and families. Sabbath observance is a major priority among Orthodox Jewish families and one scholar contends that shomer Shabbat status is the “functional equivalent” of Orthodox Jewish identity.
Various organizations have accommodated the religious observance requirements of shomer Shabbat Jews. For example, after extensive appeals on their behalf, the U.S. National High School Mock Trial Championship made adjustments for observant Jews from the Torah Academy of Bergen County who were the 2005 state champions representing New Jersey. Similarly, hospitals may allow a shomer Shabbat program for residents in medical training, in which the shomer Shabbat resident works a similar amount of hours as other residents, but not on Shabbat or major Jewish holidays. Many municipalities have cooperated with observant Jews in creating a symbolic boundary for a neighborhood (eruv), in which a shomer Shabbat is permitted to carry or move items that would otherwise be prohibited, such as a baby stroller. In sports, observant Jews may be accommodated along with Seventh-day Adventists. Alternatively, groups like Tzivos Hashem has set up its own shomer Shabbat baseball Little League.
Business implications 
Sabbath observance is also important for Jewish businesses. For example, a paper factory in Kiryat Gat was publicized in 2000 as a shomer Shabbat factory. More critically, the observance of kashrut, Jewish dietary laws, depends strongly nowadays on people who are shomer Shabbat. The mashgiach or supervisor of kashrut must be shomer Shabbat. In addition, it may be helpful if the owner is also shomer Shabbat, although this status does not necessarily mean they may be trusted with the oversight of their own establishment (Ament 2007). Conversely, a person who is not shomer Shabbat is not trusted for kashrut supervision, according to the Orthodox Union, based on a responsum of Rabbi Moshe Feinstein (Ament 2007). However, such rules do not impinge on employees or customers who may not be shomer shabbat.
As a consumer, the shomer Shabbat helps create a market demand for a range of specialty products. These products include electric timers, the blech (to keep food warm), clocks (such as "KosherClock: The Shomer Shabbat Alarm Clock with 5 Alarms"), and a Dutch oven or slow cooking pots for cholent. To avoid turning electricity on or off, the shomer Shabbat may utilize a Sabbath lamp that remains lit, yet may be covered to darken a room during Shabbat.
Cultural references 
See also 
- Judith Shulevitz. "Former Toronto rabbi says Lieberman has found a way to observe the laws of Orthodox Judaism throughout his entire political career." Toronto Star. August 12, 2000
- p.41f., Hartman Donniel. The Boundaries of Judaism. Continuum: 2007.
- Liebman, Charles. 1965 p.127. “Orthodoxy in American Jewish Life” in American Jewish Yearbook 1966.
- “Rav Simcha Weissman — Torah Pioneer and Innovator in America: First Yahrtzeit: 12 Cheshvan 5767” by M. Samsonowitz. October 25, 2006 Dei'ah Vedibur - Information & Insight 
- Data only includes synagogue members. NJPS
- Schnaidman, Mordecai (1979) “Integration in Centrist Jewish Day Schools,” Journal of Jewish Education, 47:3, 11 – 18
- “Another parent also described how she had originally sent her young son to a central Orthodox Jewish school, but found it extremely awkward when it came to socialising with other children: ‘I didn’t want my child to feel different at parties, at homes where the kids weren’t kosher, parties at McDonald’s. At one school where he went for a time, there was only one other shomer shabbat person’.” Oliver Valins. “Defending identities or segregating communities? Faith-based schooling and the UK Jewish community” in Geoforum V. 34:2, May 2003, pp. 235-247
- Faranak Margolese, Off the Derech: Why Observant Jews Leave Judaism; How to Respond to the Challenge, Devora Publishing, 2005, p. 125. ISBN 1-932687-43-2
- Elliot Kiba Ginsburg, The Sabbath in the Classical Kabbalah, SUNY Press, 1989, p. 65. ISBN 0-88706-778-6
- "US mock trial competition decides to accommodate 'shomer Shabbat' team", The Jerusalem Post, April 10, 2005. Accessed January 26, 2008.
- Rabinowitz, B . Shomer Shabbos Paper Factory Dedicated in Kiryat Gat’” in Dei'ah Vedibur - Information & Insight September 6, 2000 
- "The Big Lebowski (1998) - Memorable quotes". IMDB. Retrieved January 28, 2011.
- Ament, Jonathan. "American Jewish Religious Denominations," Report series on the National Jewish Population Survey (2000–2001), United Jewish Communities. February 2005.
- Yehoshua Neuwirth. Shemirat Shabat ke-hilkhatah. Jerusalem: Mekhon Nishmat Aharon ve-Ya'akov, 1993. (Rabbi Neuwirth often cites his teacher, Rabbi Shlomo Zalman Auerbach.)
- David ben Aryeh Leib of Lida, (ca. 1650-1696). Shomer Shabbat: bo mevoʾar kol hilkhot Shabat bi-khelal uvi-feraṭ. (Early manual for Sabbath observance). Balḳani: Yitsḥaḳ Aiziḳ Hais, 695, 1935. Originally published in 1687. (1911 edition pictured)
- Luban, Yaakov. “Current Issues Facing the Local Vaad HaKashruth.” A position paper presented by Rabbi Luban, Orthodox Union (OU), New York City, May 1, 2007. Published on the OU website as "OU Recommendations for Vaad HaKashrus Supervision." 
- Pimental, Abraham Cohen. Sefer Minchat Kohen. (Early manual for Sabbath observance). Amsterdam: David de Castro Tartas, 1668.
- Soae, Rafael Abraham, Cohen. 2004. Practical laws of Shabbat: a detailed halachic guide for the shomer Shabbat Jew. Jerusalem: Bene Aharon. (HOLLIS Number: 009507867)
- United Jewish Communities. National Jewish Population Survey 2000-2001: Strength, Challenge and Diversity in the American Jewish Population. New York: United Jewish Communities, 2003.