Code of Civil Procedure section 128.7 authorizes a trial court to order an attorney to pay sanctions where the attorney has presented claims to the court which are "presented primarily for an improper purpose, such as to harass or to cause unnecessary delay or needless increase in the cost of litigation." ( 128.7, subd. (b)(1).) An award of sanctions under section 128.7 is reviewed for abuse of discretion. (Guillemin v. Stein (2002) 104 Cal.App.4th 156, 167.) The award of sanctions is within the sound discretion of the trial court; we do not independently determine whether Simmons's conduct was frivolous and we may not substitute our judgment for the judgment of the court. (Sabek, Inc. v. Engelhard Corp. (1998) 65 Cal.App.4th 992, 1001.)