Adam Clarke on John 7:51

Doth our law judge any man - Τον ανθρωπον, the man, i.e. who is accused. Perhaps Nicodemus did not refer so much to any thing in the law of Moses, as to what was commonly practiced among them. Josephus says, Ant. b. xiv. c. 9. s. 3, That the law has forbidden any man to be put to death, though wicked, unless he be first condemned to die by the Sanhedrin. It was probably to this law, which is not expressly mentioned in the five books of Moses, that Nicodemus here alludes. See laws relative to this point, Deu 17:8, etc.; Deu 19:15.