opinion: Raymond RIVERA-LOPEZ, et al., Plaintiffs, Appellees, v. MUNICIPALITY OF DORADO, Defendant, Appellant.
  No. 92-1226.
  United States Court of Appeals, First Circuit.
  Heard Sept. 9, 1992.
  Decided Nov. 17, 1992.
  Carlos Lugo Fiol, Asst. Sol. Gen., with whom Anabelle Rodriguez, Sol. Gen., and Reina Colan de Rodriguez, Deputy Sol. Gen., were on brief for defendant, appellant.
  Arnaldo E. Granados with whom Ortiz Toro & Ortiz Brunet was on brief for plaintiffs, appellees.
  Before BREYER, Chief Judge, ALDRICH, Senior Circuit Judge, and BOUDIN, Circuit Judge.
  BAILEY ALDRICH, Senior Circuit Judge.
  Plaintiffs Raymond Rivera Lopez, et al. brought this diversity tort action in the Puerto Rico District Court against the Municipality of Dorado by a complaint filed on October 18,1990. The summons was allegedly served on one Jesús E. Palmer, Esquire, an attorney employed part-time by defendant. The local rule, adopted by the federal rule, provides for service upon the “chief executive [or] a person designated by him.” Puerto Rico R.Civ.P. 4.4(h); Fed. R.Civ.P: 4(d)(6). Defendant failed to appear and, in due course, was defaulted. Thereafter, without any attempt having been made to notify defendant, a jury trial was held to determine damages. The jury having found $300,000, judgment was entered accordingly for plaintiffs, but, within 10 days, defendant appeared specially and moved to remove the default and to vacate the judgment. Affidavits were submitted, hereinafter described.
  Defendant’s motion was referred to a magistrate judge who, according to plaintiffs’ brief, “had the discretion and opportunity to consider the credibility of the testimonies that the court had before it.” This is not, however, what he did. Rather, recognizing that both the mayor and attorney Palmer had filed affidavits to the effect that Palmer lacked authority to receive service — Palmer adding that he had so informed the process server — the magistrate invoked, instead, the doctrine of estoppel. On three previous occasions defendant had not complained of service that had been made on persons other than the mayor. Relying on this showing, the magistrate said, “The estoppel doctrine ... arises out of the general principle of equity that requires one to proceed in good faith in juridical affairs.... The previous unconditional submissions to the jurisdiction of the court ... are an implicit authorization to any complainant to follow the same procedure .... [T]he defendant is estopped by its previous acts.”
  This was a grossly enlarged view. A party claiming estoppel must show reliance, to his detriment, on a misrepresentation of facts. See Heckler v. Community Health Services of Crawford City, Inc., 467 U.S. 51, 59, 104 S.Ct. 2218, 2223, 81 L.Ed.2d 42 (1984); K-Mart Corp. v. Oriental Plaza, Inc., 875 F.2d 907, 912 (1st Cir.1989). There was no testimony that either plaintiffs or the process server relied on, or even knew of, the previous occurrences on which the magistrate predicated estoppel. While, as the magistrate said, estoppel is based on fairness, plaintiffs cannot claim unfairness by reason of something of which they were ignorant.
  We would add that this is not an estoppel case in any event. The acceptance of service in prior cases unconnected with plaintiff might have been specially authorized, or defendant, having knowledge, might have chosen to waive formalities. It should not be precluded from doing this at the cost of a general representation to the public.
  The issue here is a factual one of authority. In view of its importance, there should be a hearing on live testimony, not on conflicting affidavits. We, of course, express no opinion, but, in connection with the admissibility of the process server’s testimony that Palmer stated he was authorized, we call attention to Fed.R.Evid. 801(d)(2)(D). Though cast as a rule of evidence, this is a recital of, not a change in, the law of agency. See Union Mutual Life Ins. Co. v. Chrysler Corp., 793 F.2d 1, 8 (1st Cir.1986). Also we note the fact that, once challenged, plaintiffs have the burden of proving proper service. Saez Rivera v. Nissan Mfg. Co., 788 F.2d 819, 821 n. 2 (1st Cir.1986); Aetna Business Credit, Inc. v. Universal Decor & Exterior Design, Inc., 635 F.2d 434, 435 (5th Cir.1981). Finally, we believe that, as a matter of appearances, the new hearing should be before a new judge or magistrate. Cf. Mass.Dist.Ct. Local Rule 40.1(i).
  Reversed and remanded for further yroceedings in accordance herewith.
  . In unrelated suits, brought by other parties, defendant had appeared without contest when the service had been upon Mr. Palmer’s secretary, defendant’s Finance Director, and Mr. Palmer.
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