From Conwill v. Greenberg Traurig, LLP, 2009 U.S. Dist. LEXIS 119214 (E.D. La. Dec. 22, 2009):

Conwill urges that "once personal jurisdiction is established over Mr. Gordon for the purposes of the RICO claim, then this Court has personal jurisdiction over him for the purposes of the other claims in the Complaint that arise out of the same actionable conduct." Gordon does not dispute this Court's jurisdiction over him as to the RICO claim.

The Northern District of Texas explained the doctrine of pendent personal jurisdiction in Rolls-Royce Corp. v. Heroes, Inc.:

Pendent personal jurisdiction, like its better known cousin, supplemental subject matter jurisdiction, exists when a court possesses personal jurisdiction over a defendant for one claim, lacks an independent basis for another claim that arises out of the same nucleus of operative fact, and then, because it possesses personal jurisdiction over the first claim, asserts personal jurisdiction over the second claim.

576 F. Supp. 2d 765, 783 (N.D. Tex. 2008) (citing United States v. Botefur, 309 F.3d 1263, 1272-73 (10th Cir. 2002)); see also 4A Wright & Miller § 106.7(explaining pendent personal jurisdiction: "a district court has discretion to exercise personal jurisdiction over a claim that it ordinarily lacks jurisdiction over only when that claim arises out of the same common nucleus of operative fact as does a claim that is within the in personam jurisdiction power of the court"). "'In essence, once a district court has personal jurisdiction over a defendant for one claim, it may piggyback onto that claim other claims which arise from the same facts as the claim over which it has proper personal jurisdiction.'" Rolls Royce, 576 F. Supp. 2d at 783 (quoting Botefur, 309 F.3d at 1272) (internal quotations omitted).

Although the Fifth Circuit has not yet addressed the issue of pendent personal jurisdiction, most federal courts that have addressed it have upheld the doctrine of pendent personal jurisdiction. See 4A Wright & Miller § 106.7. As the Rolls Royce court explained:

Although the Fifth Circuit has not yet addressed this doctrine of federal common law, the Tenth Circuit has noted that every circuit court to decide the issue has approved pendent personal jurisdiction. Botefuhr, 309 F.3d at 1273; see Robinson Eng'g Co., Ltd. Pension Plan & Trust v. George, 223 F.3d 445, 449-50 (7th Cir. 2000) (applying pendent personal jurisdiction over federal claim after acquiring personal jurisdiction on related federal claim); Inamed Corp. v. Kuzmak, 249 F.3d 1356, 1362 (Fed. Cir. 2001) (authorizing pendent personal jurisdiction over declaratory judgment action when personal jurisdiction was based on federal statute); ESAB Group, Inc. v. Centricut, Inc., 126 F.3d 617, 628 (4th Cir. 1997) (holding that district court had authority to exercise pendent personal jurisdiction over state-law claims because it had personal jurisdiction over defendant on factually related federal claims); IUE AFL-CIO Pension Fund v. Herrmann, 9 F.3d 1049, 1056-57 (2d Cir. 1993) (holding that district court had personal jurisdiction over defendants as to related state-law claims on basis of pendent personal jurisdiction, because personal jurisdiction was proper over same defendants under federal statute authorizing nationwide service of process); Oetiker v. Jurid Werke, G.m.b.H., 556 F.2d 1, 4 (D.C. Cir. 1977) (approving of pendent personal jurisdiction); Robinson v. Penn Cent. Co., 484 F.2d 553, 555-56 (3d Cir. 1973) (affirming district court's exercise of pendent personal jurisdiction over state-law claims that were factually related to Securities Act claim through which defendants were served with process under statute's nationwide service of process provision). Since the Tenth Circuit's decision in Botefuhr, the Ninth Circuit has joined the other seven circuit courts in authorizing district courts to exercise pendent personal jurisdiction. See [Action Embroidery Corp. v. Atl. Embroidery, Inc., 368 F.3d 1174, 1181 (9th Cir. 2004)].

576 F. Supp.2d at 783-84.

[Footnote 36] The majority of these decisions upheld pendent personal jurisdiction over state claims where a statute providing for nationwide service of process grants the court jurisdiction over the federal claims. As the Second Circuit held, "by giving jurisdiction over an 'action to enforce a federal right, Congress granted the district courts power also to consider state law claims provided they had a nucleus of pertinent facts in common with a substantial federal claim." IUE AFL-CIO Pension Fund v. Herrmann, 9 F.3d 1049, 1056 (2d Cir. 1993) (quoting Hargrave v. Oki Nursery, Inc., 646 F.2d 716, 719 (2d Cir. 1980). The Federal Circuit has exercised pendent personal jurisdiction over a declaratory judgment action when personal jurisdiction was found as to a factually related federal claim. Inamed Corp. v. Kuzmak, 249 F.3d 1356, 1362 (Fed. Cir. 2001).