(halakha) is regarded as authoritative by the Orthodox and Conservative movements. The traditional halakhic requirements for conversion are instruction in the commandments, circumcision (if male), and immersion in an acceptable body of water before valid witnesses, and acceptance of the commandments before a rabbinical court. If a male is already circumcised, a drop of blood is drawn from the penis. Orthodox authorities require that conversions be performed in accord with traditional Jewish law and recognise only those conversions in which a convert accepts and undertakes to observe Jewish law as interpreted by Orthodox rabbis. Because rabbis in the other movements do not require that converts make this commitment, Orthodox authorities do not generally accept as valid conversions performed outside the Orthodox community. Conservative authorities likewise require that conversions be conducted according to traditional Jewish law. Conducting a conversion absent the traditional requirements of immersion in a ritual bath and circumcision for males is a violation of a Standard of the Rabbinical Assembly and grounds for expulsion. Conservative authorities generally recognize any conversion done in accord with the requirements of Jewish law, even if done outside the Conservative movement. Accordingly, Conservative rabbis may accept the validity of some conversions from other non-Orthodox movements. The Union for Reform Judaism states that "people considering conversion are expected to study Jewish theology, rituals, history, culture and customs, and to begin incorporating Jewish practices into their lives. The length and format of the course of study will vary from rabbi to rabbi and community to community, though most now require a course in basic Judaism and individual study with a rabbi, as well as attendance at services and participation in home practice and synagogue life." Its Central Conference of American Rabbis recommends that three rabbis be present for the conversion ceremony. The Rabbinical Court of the Israel Movement for Progressive Judaism requires an average of a year of study to become conversant in Jewish life and tradition. Following this, converts are required to immerse in a ritual bath, be circumcised if male, and accept the commandments before the rabbinical court. Although an infant conversion might be accepted in some circumstances (such as in the case of adopted children or children whose parents convert), children who convert would typically be asked if they want to remain Jewish after reaching religious adulthood – which is 12 years of age for a girl and 13 for a boy,