Jewish law is not directly from the laws in these books; rather, Jews follow the traditional explication of these laws that can be found in the Mishnah and in the Talmud.
According to Jewish and Christian tradition, these books were dictated by God to Moses on Mount Sinai, and constitute a word-for-word transcription of the divine word. Modern day scholars point out that the text of the Torah appears to be redacted together from a number of earlier sources; this is known as the documentary hypothesis; see JEDP theory.