What is the effect of Rule 11 sanctions in a personal injury case?

Rule 11 provides that for certain conduct, the court may impose "an appropriate sanction, which may include an order to pay ... a reasonable attorney's fee." The rule is intended to prevent frivolous filings and filings made for an improper purpose, such as personal or economic harassment. Zaldivar v. City of Los Angeles, 780 F.2d 823, 830 (9th Cir.1986). The district court's legal conclusion that Rule 11 sanctions are appropriate is reviewed de novo. Lemos v. Fencl, 828 F.2d 616, 618 (9th Cir.1987).