The paragraph mark (¶) is used in references to documents with numbered paragraphs (e.g. declarations or complaints). The section mark (§) is used in references to documents with numbered sections (e.g. statutes or motions).

A paragraph mark or section mark should always be followed by a nonbreaking space so that the mark stays joined with the numerical reference that follows. Otherwise, a line break or page break can creep in.

If the paragraph or section reference occurs at the beginning of a sentence, don’t use the mark—spell out the whole word. (“Section 17200 comes before § 17201.”)

In a reference to multiple paragraphs, double the paragraph mark (¶¶). Same for the section mark.

In citations to rules (such as the Federal Rules of Evidence, local rules of court, and rules of professional conduct), don’t use a section mark before the numerical reference (Fed. R. Evid. 801, not Fed. R. Evid. § 801).

(PS. The paragraph mark is formally known as a pilcrow.)