A district court's finding that an action was frivolous or in bad faith will not be disturbed where the district court is acting as the trier of fact and there is substantial evidence to support the decision of the district court. Dept. of Revenue v. New Life Fellowship, 217 Mont. 192, 194, 703 P.2d 860, 861 (1985). A claim is frivolous if it is outside the bounds of legitimate argument on a substantial issue on which there is a bona fide difference of opinion. Armstrong v. Dept. of Justice, 250 Mont. 468, 469-70, 820 P.2d 1273, 1274 (1991). A district court's conclusion of law that a filing violates M. R. Civ. P. 11 is reviewed de novo. Park County Concerned Citizens v. Depuy, 2008 MT 246, ¶ 15, 344 Mont. 504, 190 P.3d 293. A district court's imposition of sanctions for frivolousness under M. R. Civ. P. 11 is reviewed for abuse of discretion. Morin v. State Farm Mut. Auto. Ins. Co., 2013 MT 146, ¶ 33, 370 Mont. 305, 302 P.3d 96.