opinion: UNITED STATES of America, et al., Plaintiffs, and State of California, Plaintiff-Counter-Defendant-Appellant, v. J.B. STRINGFELLOW, Jr., et al., Defendants-Counter-Claimants-Appellees.
  No. 89-55500.
  United States Court of Appeals, Ninth Circuit.
  Argued and Submitted June 5, 1990.
  Decided Aug. 10, 1990.
  See also, D.C., 661 F.Supp. 1053.
  Marcelle E. Mihaila and Kenneth S. Klein, Gray, Cary, Ames & Frye, San Diego, Cal., for plaintiff-counter-defendant-appellant.
  Robert P. Dahlquist and Richard W. Raushenbush, Latham & Watkins, San Diego, Cal., for defendants-counter-claimants-appellees.
  Before BROWNING and PREGERSON, Circuit Judges, and COPPLE, District Judge.
  The Honorable William P. Copple, Senior Judge, United States District Court for the District of Arizona, sitting by designation.
  PER CURIAM:
  Kammer, an attorney for the State of California, filed a motion for judgment on the pleadings on the ground appellees’ counterclaims against the State were preempted by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The magistrate, whose findings were adopted by the district court, denied the motion and sanctioned Kammer for failing to cite a Northern District of Illinois case and certain CERCLA provisions. We reverse.
  The facts forming the basis of the sanctions are not disputed. Only the legal conclusion that those facts constitute a violation of Rule 11 is at issue. Rule 11 determinations are reviewed for abuse of discretion. Cooter & Gell v. Hartmarx Corp., — U.S.-, 110 S.Ct. 2447, 2461, 110 L.Ed.2d 359 (1990).
  The failure to cite relevant authority, whether it be case law or statutory provisions, does not alone justify the imposition of sanctions. “[NJeither Rule 11 nor any other rule imposes a requirement that the lawyer, in addition to advocating the cause of his client, step first into the shoes of opposing counsel to find all potentially contrary authority, and finally into the robes of the judge to decide whether the authority is indeed contrary or whether it is distinguishable.” Golden Eagle Distrib. Corp. v. Burroughs Corp., 801 F.2d 1531, 1542 (9th Cir.1986).
  However, if the omitted case law and statutory provisions would render the attorney’s argument frivolous, he or she “should not be able to proceed with impunity in real or feigned ignorance of [them],” id., and sanctions should be upheld. An argument contained in a motion is frivolous under Rule 11 if it is unreasonable when viewed from the perspective of “a competent attorney admitted to practice before the district court.” Zaldivar v. City of Los Angeles, 780 F.2d 823, 830 (9th Cir.1986); see also Eastway Constr. Corp. v. City of New York, 762 F.2d 243, 254 (2d Cir.1985) (“[WJhere it is patently clear that a claim has absolutely no chance of success under the existing precedents, and where no reasonable argument can be advanced to extend, modify or reverse the law as it stands, Rule 11 has been violated.”).
  Counsel for the State argued that a party liable under CERCLA for response costs who seeks contribution from another party may proceed only under CERCLA when the second party is also liable or potentially liable under CERCLA. This argument is plausibly supported by the language of 42 U.S.C. § 9613(f)(1). Appellees argue the State’s motion is frivolous because the last sentence of § 9613(f)(1) “saves” all other actions for contribution or indemnification. We think the last sentence of § 9613(f)(1) could plausibly be read to save state law and federal common law actions for contribution or indemnification only in those instances when the first party is not liable under CERCLA.
  Edward Hines Lumber Co. v. Vulcan Materials Co., 685 F.Supp. 651 (N.D.Ill.1988), is relevant but distinguishable. Hines concerns parties who are not liable for contribution under CERCLA. Id. at 658. The State argues § 9613(f)(1) is the exclusive remedy for parties who are liable for contribution under CERCLA. Even if Hines were directly on point, a holding by the Northern District of Illinois would not render the State’s motion to a district court in this circuit frivolous.
  While 42 U.S.C. §§ 9607(e)(1) and (2), 9614(a) and (b), and 9652(d) are relevant to the interpretation of § 9613(f)(1), they do not preclude the conclusion for which the State argues. A court could plausibly interpret §§ 9607(e)(1), (2), 9614(a), (b), and 9652(d) as saving obligations and liabilities other than the obligation to contribute arising under CERCLA. Since the omitted case law and statutory provisions would not have rendered the State’s argument frivolous, it was an abuse of discretion to sanction counsel for the omission. Cooter & Gell, 110 S.Ct. at 2461.
  REVERSED.
  . Appellees also contend on appeal that the motion was filed for improper purposes. But if the motion is not frivolous, it cannot fall within the "improper purpose" clause of Rule 11. Golden Eagle, 801 F.2d at 1538.
  . Section 9613(f)(1) provides:
  Any person may seek contribution from any other person who is liable or potentially liable under section 9607(a) of this title, during or following any civil action under section 9606 of this title or under section 9607(a) of this title. Such claims shall be brought in accordance with this section and the Federal Rules of Civil Procedure, and shall be governed by Federal law. In resolving contribution claims, the court may allocate response costs among liable parties using such equitable factors as the court determines are appropriate. Nothing in this subsection shall diminish the right of any person to bring an action for contribution in the absence of a civil action under section 9606 or section 9607 of this title.
  42 U.S.C. § 9613(f)(1) (1986).
instruction: What follows is an opinion from a United States Court of Appeals.
  Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
  In some cases there is some confusion over who should be listed as the appellant and who as the respondent. This confusion is primarily the result of the presence of multiple docket numbers consolidated into a single appeal that is disposed of by a single opinion. Most frequently, this occurs when there are cross appeals and/or when one litigant sued (or was sued by) multiple litigants that were originally filed in district court as separate actions. The coding rule followed in such cases should be to go strictly by the designation provided in the title of the case. The first person listed in the title as the appellant should be coded as the appellant even if they subsequently appeared in a second docket number as the respondent and regardless of who was characterized as the appellant in the opinion.
  To clarify the coding conventions, consider the following hypothetical case in which the US Justice Department sues a labor union to strike down a racially discriminatory seniority system and the corporation (siding with the position of its union) simultaneously sues the government to get an injunction to block enforcement of the relevant civil rights law. From a district court decision that consolidated the two suits and declared the seniority system illegal but refused to impose financial penalties on the union, the corporation appeals and the government and union file cross appeals from the decision in the suit brought by the government. Assume the case was listed in the Federal Reporter as follows:
  United States of America,
  Plaintiff, Appellant
  v
  International Brotherhood of Widget Workers,AFL-CIO
  Defendant, Appellee.
  International Brotherhood of Widget Workers,AFL-CIO
  Defendants, Cross-appellants
  v
  United States of America.
  Widgets, Inc. & Susan Kuersten Sheehan, President & Chairman
  of the Board
  Plaintiff, Appellants,
  v
  United States of America,
  Defendant, Appellee.
  This case should be coded as follows:Appellant = United States, Respondents = International Brotherhood of Widget Workers Widgets, Inc., Total number of appellants = 1, Number of appellants that fall into the category "the federal government, its agencies, and officials" = 1, Total number of respondents = 3, Number of respondents that fall into the category "private business and its executives" = 2, Number of respondents that fall into the category "groups and associations" = 1.
  Your task is to identify the state of the first listed state or local government agency that is an appellant.
choices: not Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachussets Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New New New New North North Ohio Oklahoma Oregon Pennsylvania Rhode South South Tennessee Texas Utah Vermont Virginia Washington West Wisconsin Wyoming Virgin Puerto District Guam not Panama