Florida Federal Court Rejects Personal Jurisdiction Over Nonresidents Mark Cuban and the Dallas Mavericks Based Solely on Their Global Promotional Activities

A Florida federal court recently dismissed a putative class action against Mark Cuban and the Dallas Mavericks, two Texas-based defendants represented by Brown Rudnick LLP, for allegedly promoting a cryptocurrency scheme. The court held that the defendants’ purported global promotional activities did not establish personal jurisdiction over them in Florida. The decision in Karnas v. Cuban (S.D. Fla. Dec. 30, 2025), involving Mr. Cuban’s and the Mavericks’ alleged promotion of Voyager Digital’s cryptocurrency investing application, emphasizes that internet-based and other promotional activity must be aimed at the applicable forum to establish personal jurisdiction and that globally directed marketing activities will not suffice even if they happen to reach forum residents.

The Karnas decision is highly relevant these days for its discussion of jurisdictional issues in the context of electronic media with worldwide scope. But it also is interesting for its analysis of the conspiracy theory of personal jurisdiction. The U.S. District Court for the Southern District of Florida (Judge Roy K. Altman) held that plaintiffs had not satisfied that alternative theory of jurisdiction because they had not pled the existence of any agreement between the Texas-based defendants and the Florida-based alleged co-conspirators. But the court also questioned the theory’s validity, concluding that it “stands in tension with the Supreme Court’s admonition that ‘[e]ach defendant’s contacts with the forum state must be assessed individually.’”

Factual Background
The Karnas class action arose out of the collapse of Voyager, which operated a platform that allowed users to access multiple cryptocurrencies and cryptocurrency exchanges. Plaintiffs sued Mr. Cuban and the Mavericks for allegedly promoting the Voyager platform pursuant to a “five-year exclusive, integrated partnership.” Those alleged activities consisted of:

• Mr. Cuban’s remarks at a press conference livestreamed from Dallas;
• A Mavericks promotion to users anywhere in the world who downloaded the Voyager app;
• Mr. Cuban’s press release about the Mavericks’ “partnership” with Voyager;
• Mr. Cuban’s trips to Florida to attend cryptocurrency conferences; and
• The visibility of Voyager advertisements at several of the Mavericks’ Dallas home games, which were streamed nationwide.

Plaintiffs asserted claims under various state securities and consumer-protection statutes against Mr. Cuban, the Mavericks, and two Florida residents (who later settled). Mr. Cuban and the Mavericks moved to dismiss on numerous grounds, including lack of personal jurisdiction in Florida. The court granted the motion on that latter ground.

Court’s Decision
Plaintiffs sought to establish personal jurisdiction under three prongs of Florida’s long-arm statute. The court rebuffed all three attempts.

First, the court rejected the argument (which plaintiffs abandoned) that jurisdiction existed based on defendants’ allegedly having “caused injury” in Florida by engaging in “solicitation or service activities within this state” (§ 48.193(1)(a)(6)). The court ruled that, under Florida law, “economic injury unaccompanied by physical injury or property damage, is insufficient to subject a non-resident defendant to personal jurisdiction under” that provision.

Second, the court rejected the contention (which plaintiffs also abandoned) that jurisdiction could be based on defendants’ allegedly “operating, conducting, engaging in, or carrying on a business or business venture in this state or having an office or agency in this state” (§ 48.193(1)(a)(1)). Plaintiffs had not established that defendants had agents or offices in Florida or had any other business connections with the state. Mr. Cuban’s condos in and travels to Florida did not satisfy the statutory requirements. Nor did the Mavericks’ “electronic communications from out-of-state offices into Florida . . . establish conducting business in Florida.”

Third, the court rejected plaintiffs’ main argument: the existence of jurisdiction under § 48.193(1)(a)(2) for causes of action arising from “[c]ommitting a tortious act within this state.” Plaintiffs sought to proceed under two jurisdictional theories: the “intentional-tort theory” and the “conspiracy theory.” Neither effort succeeded.

To try to establish an intentional tort, plaintiffs alleged that defendants had “intentionally availed themselves of the Florida consumer market through the targeted promotion, marketing, and sale of Voyager’s [cryptocurrency] in Florida, which constitutes a tortious act within the state of Florida.” The court held that plaintiffs had not satisfied this standard because they had not shown that defendants had committed “intentional torts specifically aimed at a Florida resident.” Focusing on issues that frequently arise with digital activity, the court noted that the allegedly improper activity here had been aimed at national (if not worldwide) audiences, not specifically at Florida residents. Mere knowledge that global promotional activity would reach Floridians is not enough. Defendants’ “posting information on the internet is not sufficient by itself to subject [them] to personal jurisdiction in each State in which the information is accessed.”

Alternatively, plaintiffs contended that personal jurisdiction existed under a “conspiracy theory” because Mr. Cuban and the Mavericks allegedly had conspired with the two Florida-based defendants. The court rejected this gambit because plaintiffs had not sufficiently alleged an agreement among the Texas-based defendants and the two Floridians – or even that the Texas defendants had interacted with the Florida defendants or had known that the Floridians had partnered with Voyager. The court noted that, while Voyager might have had separate agreements with each set of defendants, Voyager’s agreements were not the Texas defendants’ agreements and thus could not establish a conspiracy between the Texas and the Florida defendants.

Perhaps more interesting, though, is the court’s skepticism about the entire theory of conspiracy-based personal jurisdiction. The court observed that the theory is in tension with the Supreme Court’s emphasis on assessing each defendant’s contacts with the forum individually, and it noted the spectrum of approaches within the federal judiciary: some Circuits have not endorsed any version of conspiracy jurisdiction; one (the Second Circuit) has embraced it; and others have “straddle[d] a line of ambivalence.” The court opined that any version of conspiracy jurisdiction should require the defendant to “control a co-conspirator” before the co-conspirator’s purposeful availment of the particular forum can be attributed to the first defendant. “Tethering the doctrine to agency principles prevents conspiracy jurisdiction from swallowing the due-process values that are enshrined in the personal-jurisdiction inquiry.” The court also suggested that the Supreme Court reexamine the viability of the conspiracy-jurisdiction doctrine.

Implications
The Florida court’s jurisdictional ruling should be useful to alleged promoters of cryptocurrencies and other products or services if those promoters are sued based on their national or global internet and media activities. If a promoter’s efforts do not focus on or target audiences in a particular forum, and if the promoter otherwise lacks sufficient contacts with that forum, the promoter’s national or worldwide activities likely will not be enough to establish personal jurisdiction in that forum.

We will see whether the court’s views on the conspiracy theory of jurisdiction cause a rethinking or narrowing of the doctrine’s viability. As the court noted, the doctrine might make sense where the defendant controlled or had an agency relationship with the alleged co-conspirator. But without some type of control or agency relationship, the doctrine might too easily evade the need to examine each defendant’s individual contacts with the forum at issue.