From Rockwood Retaining Walls, Inc. v. Patterson, Thuente, Skaar & Christensen, P.A., 2009 U.S. Dist. LEXIS 119349 (D. Minn. Dec. 22, 2009):

The Federal Circuit has held that federal courts have jurisdiction over malpractice actions alleging sub-standard legal representation in patent prosecution and litigation suits if "the patent infringement question is a necessary element of [the] malpractice claim and raises a substantial, contested question of patent law that Congress intended for resolution in federal court." Air Measurement Tech., Inc. v. Akin Gump Strauss Hauer & Feld, L.L.P., 504 F.3d 1262, 1265 (Fed. Cir. 2007). Because the malpractice law of the relevant state required the plaintiff to "establish that they would have prevailed in the prior litigation but for [their counsel's] negligence," the malpractice action involved "the 'case within a case' requirement of the proximate cause element of malpractice." Id. at 1268-69. Thus, "[b]ecause the underlying suit here is a patent infringement action . . ., the district court will have to adjudicate, hypothetically, the merits of the infringement claim." Id. at 1269. Accordingly, there was "simply no good reason to deny federal jurisdiction." Id.

[Footnote 2] Plaintiffs attempt to distinguish Air Measurement Technologies on the basis that there the party alleging malpractice was also the plaintiff in the underlying patent action, whereas here Plaintiffs were the alleged infringers in the underlying action. *** Plaintiffs thus contend that a claim does not arise under the patent laws if the "'patent issue appears only in a defense to that claim.'" . . . (quoting Air Measurement Technologies, 504 F.3d at 1268)***. But Plaintiffs misconstrue the well-pleaded Complaint rule. Granted, to satisfy federal question jurisdiction the federal claim must appear on the face of the plaintiff's well-pleaded complaint, not in a defense, but the fact that Plaintiffs here were the defendants in the underlying patent action does not negate the fact that here Plaintiffs' Amended Complaint discloses the federal question. The federal question is not gleaned from Defendant's Answer or the Court's anticipation of any federal defense the Law Firm might raise.

[Footnote 3] In a second decision issued the same day as Air Measurement Technologies, the Federal Circuit reiterated its reasoning and holding in the context of a malpractice action alleging that counsel was negligent in its drafting of a patent claim. Immunocept, LLC v. Fulbright & Jaworski, LLP, 504 F.3d 1281, 1284-85 (Fed. Cir. 2007) (holding that federal jurisdiction existed over malpractice action because where claim-drafting error is sole basis of alleged negligence, "there is no way [plaintiff] can prevail without addressing claim scope" and "[b]ecause patent claim scope defines the scope of patent protection, we surely consider claim scope to be a substantial question of patent law"). And more recently, in Touchcom, Inc. v. Bereskin & Barr , the Federal Circuit adhered to its decisions in Air Measurement Technologies and Immunocept. 574 F.3d 1403 (Fed. Cir. 2009).