Per Curiam.

In this action for vexatious suit and for tortious interference with a contractual relationship, which the plaintiffs claimed to the jury, the trial court bifurcated the issues and ordered the question of lack of probable cause 1 tried to the *671 court. Thereafter the court dismissed the action for failure of the plaintiffs to make out a prima facie case.

Probable cause is the knowledge of facts sufficient to justify a reasonable man in the belief that he has reasonable grounds for presenting an action. Paranto v. Ball, 132 Conn. 568, 571, 46 A.2d 6 (1946). Its existence or nonexistence is determined by the court on the facts found. Zitkov v. Zaleski, 102 Conn. 439, 445, 128 A. 779 (1925). In those cases, the facts were not in dispute and consequently the determination of the ultimate fact of probable cause was a question of law. When, however, the underlying facts are in dispute there is a constitutional right to have those facts determined by a jury. Rickert v. Fraser, 152 Conn. 678, 681, 211 A.2d 702 (1965).

There is error, the judgment is set aside and the case is remanded for further proceedings according to law.

Because the resolution of the probable cause issue is dispositive of this appeal we merely note that in actions of tortious interference the burden of showing that the interference is privileged or justified is on the defendant. Harry A. Finman & Son, Inc. v. Connecticut Truck & Trailer Service Co., 169 Conn. 407, 415, 363 A.2d 86 (1975). Whether because of the relationship of the two causes of actions in the complaint the rule is applicable in this case we do not decide.