OPINION OF THE COURT
GIBBONS, Circuit Judge.Greate Bay Hotel and Casino, Inc. (Greate Bay) appeals from a final judgment of $105,000 in favor of David Prinz in his suit for false imprisonment and assault and battery, and from an order denying its motions for judgment notwithstanding the verdict and for a new trial. The judgment was entered on a jury verdict on special verdict interrogatories, which found Greate Bay liable for assault and battery and false imprisonment and awarded $5,000 in compensatory and $100,000 in punitive damages. We hold that the trial court erred in denying Greate Bay’s motion for a new trial, and we remand for that purpose.
Greate Bay operates a gambling casino in Atlantic City, New Jersey, which includes a number of blackjack tables. On the evening of May 20,1981 Prinz an identified card counter was observed playing blackjack in the casino. At that time Greate Bay had a policy against permitting card counters to play blackjack. Prior to May 20, 1981, Prinz had been advised by employees of Greate Bay that, if he attempted to play, he would be ejected as a trespasser. On May 20 employees of Greate Bay advised Prinz to leave or he would be arrested. As the employees escorted him toward the exit, however, a scuffle broke out in the lobby. Prinz was knocked to the floor, handcuffed, and removed to a detention cell in the premises. The Atlantic City police were called and transported Prinz from the detention cell to the police station. There an employee of Greate Bay filed a complaint for defiant trespassing in violation of NJ.Stat.Ann. 2C:18-3(b) (West 1982), and the police made a criminal charge against him.1
Prinz was held in the police station for approximately 20 hours. On the morning of May 21, 1981, after conferring with a public defender assigned to the Atlantic City Municipal Court, Prinz appeared in that court, entered a guilty plea to the defiant trespassing charge, and paid a small fine.
In November of 1981 Prinz filed a diversity action against Greate Bay, charging assault and battery and false imprisonment. In its answer Greate Bay pleaded:
The allegations of false imprisonment are denied. To the contrary, defendant was detained pending the arrival of the Atlantic City Police Department and plaintiff was charged and convicted of defiant trespass.
Appellant’s Appendix at 8a (hereinafter designated by page number and “a”). Thus Greate Bay alleged facts which would bar Prinz’ false imprisonment claim by virtue of collateral estoppel. See Kauffman v. Moss, 420 F.2d 1270, 1274 (3d Cir.1970); United States v. Schneider, 139 F.Supp. 826, 829 (S.D.N.Y.1956). The answer did not, however, plead collateral estoppel as an affirmative defense. See Fed.R.Civ.P. 8(c).
At trial counsel for Greate Bay elicited testimony from Prinz without objection:
Q. Now concerning the Atlantic City Police Department, the charges there, you pleaded guilty to those charges, didn’t you?
A. That’s correct, sir.
58a. Thus there is uncontradicted record evidence which would permit, and probably require, a finding of collateral estoppel on *694the false imprisonment charge. At the end of the plaintiff’s case, Greate Bay moved for a directed verdict on several grounds, among them:
Then the false imprisonment claim, that he was detained while the Atlantic City Police were called. He was arrested by the Atlantic City Police and eventually pleaded guilty. I submit, your Honor, that that would preclude his false imprisonment claim.
75a. The trial court, without explanation, denied the motion. It was renewed at the end of the entire case and again denied without explanation. 197a. Greate Bay then requested a charge respecting the false imprisonment claim:
You must consider the fact that the Atlantic City Police Department was notified immediately and took plaintiff into custody and charged him with defiant trespassing. Plaintiff has admitted that he pleaded guilty to this offense.
266a. The court refused this charge, again without explanation. The jury was not given any instruction about the possible significance of the guilty plea. Instead the court, over objection charged:
Now, the defendant claims that its employees made a lawful civil arrest of the plaintiff for committing the petty disorderly person’s offense of defiant trespass. I instruct you as a matter of law that defendant’s employees did not have legal authority to arrest the plaintiff for defiant trespass, because, as I told you earlier, the defendant did not have the right to exclude the plaintiff from the casino as a suspected card counter. Therefore, if you find from the evidence that the plaintiff has proven that defendant’s employees intentionally detained him against his will, by actual force, for some appreciable period of time, then you should find the defendant liable for false imprisonment.
238-39a.
Greate Bay contended in the trial court, and contends here, that the quoted portion of the charge is a misstatement of the New Jersey law in effect on May 20, 1981 respecting its obligation to permit card counters to play blackjack in its casinos.2 But more significantly for present purposes, Greate Bay argues that the court’s virtual directed verdict on the false imprisonment charge removed from the jury’s consideration the fact that Prinz’ guilty plea to the charge of defiant trespass estopped him from contending that he could lawfully remain in the casino. If he could not lawfully remain there was probable cause for his detention as a defiant trespasser, which in New Jersey is a defense to a charge of false imprisonment. E.g., Jorgensen v. Pennsylvania Railroad Co., 38 N.J.Super. 317, 349, 118 A.2d 854, 872 (App.Div.1955).
In response, Prinz relies on Rule 8(c). He contends that an affirmative defense not pleaded in the district court is not available on appeal. That is the general rule. Sartin v. Commissioner of Public Safety, 535 F.2d 430, 433 (8th Cir.1976). However, Fed.R.Civ.P. 15(c) must also be taken into account. It provides that issues tried by the express or implied consent of the parties “shall be treated in all respects as if they had been raised in the pleadings.” Professor Moore notes:
If an affirmative defense is not pleaded it is waived to the extent that the party who should have pleaded the affirmative defense may not introduce evidence in support thereof, unless the adverse party makes no objection in which case the issues are enlarged.. ..
2A Moore’s Federal Practice ¶¶ 8.27[3] at 8-251, 8-253 (2d ed. 1981). The rule is particularly applicable where, as here, the facts underlying the affirmative defense have been pleaded. Federal Savings and Loan Insurance Corporation v. Hogan, 476 F.2d 1182, 1186 (7th Cir.1973).
Here the facts on which the defense of collateral estoppel rests were pleaded in *695the answer. They were introduced in evidence without objection. They were called to the court’s attention in a motion for directed verdict, which was renewed at the end of the entire case. They were the subject of a timely request for charge. Prinz does not suggest that he has any evidence which might have been offered to overcome the collateral estoppel effect of his guilty plea. In this totality of circumstances Rule 15(c) rather than Rule 8(c) provides the appropriate frame of reference.
Because the collateral estoppel defense, although tried, was taken from the jury, the verdict cannot stand. The assault and battery verdict does not suffer from the same defect as the false imprisonment verdict, but because the jury did not make separate damage awards the two are inseparable.
The order denying Greate Bay’s motion for a new trial will be reversed and the case remanded for that purpose.
. N.J.Stat.Ann. 2C:18-3(b) (West 1982) provides:
A person commits a petty disorderly persons offense if, knowing that he is not licensed or privileged to do so, he enters or remains in any place as to which notice against trespass has been given by: (1) Actual communication to the actor ....
. The law was far from certain. See Uston v. Resorts International Hotel, Inc., 89 N.J. 163, 445 A.2d 370 (1982).