The relative pronouns that, which, and who are used to join a dependent clause to the rest of the sentence. They “relate” the clause back to a noun.
· The house that the defendant lived in was on
Street. (clause relates or refers back to
the noun “house”)
If the clause relates to a person, use who. If the clause relates to a thing, use that if the clause is restrictive and which if the clause is nonrestrictive. “Restrictive” means that the clause restricts the meaning of the noun—it helps identify the noun. “Nonrestrictive” means that the clause does not restrict the meaning of the noun, but merely provides additional information about a noun that has already been fully identified.
Clauses beginning with which are nonrestrictive and should be set off with commas; that clauses are restrictive and should not be set off with commas. Who clauses can be restrictive or nonrestrictive.
· The driver who hit the green car was seriously injured. (clause refers to a person and is restrictive because it identifies the specific driver being referred to, so use who with no commas)
· The car that the police were chasing reached the intersection first. (clause refers to a thing and is restrictive because it identifies the specific car being referred to, so use that with no commas)
· The blue car, which entered the intersection after the accident, was not speeding. (clause refers to a thing and is nonrestrictive because it is not needed to understand which car is being referred to, so use which with commas)
Relative clauses that follow proper nouns are nonrestrictive; the reader understands what the noun is without the information in the clause.
· Justice O’Connor, who wrote the dissenting opinion, applied a novel analysis. (clause refers to a person who is completely identified by name, so it is nonrestrictive--use who with commas)
Anne Enquist & Laurel Currie Oates, Just Writing 215-20, 311 (3d ed. 2009); Laurel Currie Oates & Anne Enquist, The Legal Writing Handbook 656-58 (5th ed. 2010).