Use the section symbol

Error²Federal courts, Illinois courts21st and 22nd editions

“Cal. Penal Code § 187”, not “Cal. Penal Code section 187”: inside a state-code citation the symbol is used, except where the state sets its own designator.¹

1. 1R. 6.2(c) Section (§) and paragraph (¶) symbols.
2. 2An error: the rule in note 1 allows one form, and this is not it.