Source: https://boards.answers.findlaw.com/topic/242711-definition-of-conspiracy-theory-in-law/?tab=comments
Timestamp: 2019-04-20 00:11:58+00:00

Document:
Can someone point me to a definition of the term 'conspiracy theory' as used in criminal and/or civil law?
Oh, so you already know the answer.
Good, no need to bother us on various legal websites.
I think we are in troll territory. This poster is on 4 sites asking the same question and every time there's an answer his response is "that's not right" and proceeds to cite cases.
You didn't identify a state or other jurisdiction, but I'm not aware of any U.S. state or federal law that defines the term "conspiracy theory." The term "conspiracy" is commonly used in criminal law (and, in some states, in civil law). However, unless you identify a state or jurisdiction, it's impossible to point you to a particular definition.
To our knowledge, the United States Supreme Court, as yet, has not definitively examined the conspiracy theory of jurisdiction. We must therefore attempt to formulate a workable standard, recognizing that evolution will inevitably call for refinement. The conspiracy theory rests in part upon the legal premise that the acts of a conspirator are imputed to all the other co-conspirators. We believe a strict test, modeled after the ones used in cases which have previously recognized the conspiracy theory of jurisdiction, withstands due process scrutiny. We therefore hold that a conspirator who is absent from the forum state is subject to the jurisdiction of the court, assuming he is properly served under state law, if the plaintiff can make a factual showing that: (1) a conspiracy to defraud existed; (2) the defendant was a member of that conspiracy; (3) a substantial act or substantial effect in furtherance of the conspiracy occurred in the forum state; (4) the defendant knew or had reason to know of the act in the forum state or that acts outside the forum state would have an effect in the forum state; and (5) the act in, or effect on, the forum state was a direct and foreseeable result of the conduct in furtherance of the conspiracy.
Textor v. Bd. of Regents, 711 F.2d 1387 (7th Cir. 1983).
There does not seem to be any question that if plaintiff's complaint alleges an actionable conspiracy then the minimum contacts test has been met. The "conspiracy theory" of personal jurisdiction is based on the "time honored notion that the acts of [a] conspirator in furtherance of a conspiracy may be attributed to the other members of the conspiracy." Gemini Enterprises, Inc. v. WFMY Television Corp., supra, 470 F.Supp. at 564; see also National Van Lines, Inc. v. Atlas Van Lines, Inc., 406 F.Supp. 1087 (N.D.Ill.1975); Socialist Workers Party v. Attorney General, 375 F.Supp. 318, 321 (S.D.N.Y.1974), vacated on other grounds, 510 F.2d 253, 257 (2nd Cir.1974); Mandelkorn v. Patrick, 359 F.Supp. 692 (D.D.C.1973); Green v. Advance Ross Electronics Corp., 86 Ill.2d 431, 440-441, 56 Ill.Dec. 657, 662, 427 N.E.2d 1203, 1208 (1981). To plead successfully facts supporting application of the conspiracy theory of jurisdiction a plaintiff must allege both an actionable conspiracy and a substantial act in furtherance of the conspiracy performed in the forum state. Gemini Enterprises, Inc. v. WFMY Television Corp., supra, at 564. If plaintiff's allegations are sufficient to establish both of these elements then it was an abuse of the district court's discretion to refuse plaintiff leave to amend.
FWIW, these cases refer to a jurisdictional theory used in cases in which conspiracy is alleged. They don't state "a definition of the term 'conspiracy theory.'"

References: v. 
 v. 
 v. 
 v. 
 v. 
 v. 
 v.