This is an appeal from an order denying appellants’ petition for leave to file an amended answer, with new matter pleading the affirmative defense of comparative negligence.1 Appellants now contend that the denial constituted an abuse of discretion on the part of the trial court. Upon review of the record, and the briefs of counsel, we now affirm.
This matter arises from an automobile accident which occurred on May 26, 1983, at approximately 6:00 p.m., near the intersection of Route 100 and Spring Creek Road, in Lower Macungie Township, Lehigh County. Appellee Gloria Grim was operating a 1983 Chevrolet Monte Carlo north on Route 100, when a tractor trailer operated by appellant James H. Betz, in his capacity as an employee of appellant Dallas and Mavis Forwarding Company,2 careened out of control on the wet pavement, across the center line of Route 100 into the oncoming lane of traffic, thereby colliding head-on with the Grim vehicle. Richard Grim, Gloria’s three year old son, received severe internal injuries, and died later that evening. The remaining occupants of the Grim vehicle, including Gloria; Gloria’s seven year old son, Robert; Gloria’s sister-in-law, Susan Grim; and Susan’s two minor children, Amy, age eleven, and Donna, age six, received injuries of varying severity. Gloria and Susan were occupying the front seat of the vehicle at the time of the accident, while all four minor children were seated in the rear passenger seat. None of the occupants in the Grim vehicle were wearing seat belts or other restraining devices.
*617On July 25, 1984, two separate suits were filed in the Court of Common Pleas of Lehigh County. In the first action, the named plaintiffs were Larry and Gloria Grim, in their own right, and as the parents and natural guardians of Robert Grim,3 while in the second action, suit was filed by Bruce and Susan Grim, in their own right, and as the parents and natural guardians of Amy Grim and Donna Grim. The named defendants in both actions were James H. Betz, Dallas and Mavis Forwarding Company, Columbus Truck Center, Inc., and the Commonwealth of Pennsylvania, Department of Transportation.4 On February 28, 1985, both complaints were amended to add Freightliner Corporation as a named defendant, by stipulation of the parties.
After pleading and discovery had proceeded for approximately one year, appellants Betz, and Dallas and Mavis, filed a petition for leave to file an amended answer and new matter in both actions, in order to plead the following:
8. After a thorough review of the records and information received from plaintiffs, Betz and Dallas have concluded that use of seatbelts and/or a child restraining seat by the occupants of the plaintiffs’ vehicle would have prevented and/or mitigated the injuries suffered by the plaintiffs.
9. Betz and Dallas aver that plaintiffs Gloria Grim and Susan Grim may be liable on each of the minor plaintiffs’ claims due to their failure to have their children use seat belts and/or child restraining seats.
10. Betz and Dallas aver that plaintiff Susan Grim and plaintiff Gloria Grim may be comparatively negligent for their failure to wear their seat belts.
11. Betz and Dallas request leave to file an Amended Answer with New Matter so as to join plaintiffs Gloria Grim and Susan Grim as, additional defendants under Pa.R.C.P. 2252(d) and also to plead Susan Grim’s and *618Gloria Grim’s comparative negligence as an affirmative defense.
Appellant Freightliner Corporation joined in this petition, and filed a separate memorandum of law. On March 31, 1986, the petition was denied as a “violation of a positive rule of law”. All appellants timely appealed, and the appeals were consolidated by stipulation of the parties, pursuant to Pa.R.A.P. 513.
Pa.R.C.P. 1033 states:
A party, either by filed consent of the adverse party or by leave of court, may at any time change the form of action, correct the name of a party or amend his pleading. The amended pleading may aver transactions or occurrences which have happened before or after the filing of the original pleading, even though they give rise to a new cause of action or defense. An amendment may be made to conform the pleading to the evidence offered or admitted.
The courts of this Commonwealth have been liberal in permitting the amendment of pleadings. Gallo v. Yamaha Motor Corp., U.S.A., 335 Pa.Super. 311, 484 A.2d 148, 150 (1984); Tanner v. Allstate Ins. Co., 321 Pa.Super. 132, 467 A.2d 1164, 1167 (1983). Their discretion, however, is not unfettered; a defendant will not be permitted to amend his answer, to plead a new defense, where surprise or prejudice to the plaintiff will result, or where the proposed amendment is against a positive rule of law. Posternack v. American Casualty Co., 421 Pa. 21, 218 A.2d 350, 351-52 (1960); Goodrich Amram 2d § 1033.7.
Appellants contend that the trial court erred in finding that their request to amend, in order to plead a “seat belt defense”, was contrary to a positive rule of law.5 Appellants cite to the decision in Parise v. Fehnel, 267 Pa.Super. 79, 406 A.2d 345 (1979), in support of their *619position that the availability of a “seat belt defense” remains an open question in Pennsylvania. In Parise, a panel of this Court held that, in the absence of expert testimony demonstrating a causal connection between the plaintiffs injuries and plaintiffs failure to wear a seat belt, it was not error on the part of the trial court to refuse to instruct the jury that the failure to use a seat belt could be evidence of contributory negligence on the issue of damages. Id., 406 A.2d at p. 347. However, Parise also contained the following language with respect to the existence, per se, of a “seat belt defense”:
“Our decision today should not be seen as foreclosing the possibility of a so-called ‘seat belt defense’ in future cases____ (t)he New Jersey Superior Court said that it might have allowed the defendant a seat belt defense if he had introduced expert testimony showing a relationship between the plaintiffs injuries and his failure to use seat belts (cites omitted)____ That is our position." (Emphasis supplied.)
Id. As such, it would appear that appellants are substantially correct in their assertions that the trial court’s decision to preclude amendment to plead a “seat belt defense”, as contrary to law, was erroneous on the basis of the state of the law on March 31, 1986.6
*620However, a reviewing court may affirm the decision of the trial court if the result is correct on any ground, without regard to the grounds relied upon by the trial court. Butler v. DeLuca, 329 Pa.Super. 383, 478 A.2d 840, 843 (1984). Moreover, it is well settled that an intervening change in the law must be applied to cases which are in the throes of direct appeal when the change occurs. Leland v. J.T. Baker Chemical Co., 282 Pa.Super. 573, 423 A.2d 393, 396 (1980). We find that an intervening change in the law has occurred which mandates affirmance of the trial court’s denial of permission to amend.
On November 23, 1987, the availability of a “seat belt defense” in Pennsylvania, ceased to be an open question, with the passage of Act 82 of 1987. Section 5 of that Act amends the Child Passenger Protection Act, 75 Pa.C.S. §§ 4581-85, to become the Occupant Protection Act. The relevant provisions of Section 5, which amend 75 Pa.C.S. § 4581, read as follows:
§ 4581. Restraint Systems.
(A) [Child Passenger] Occupant Protection. —[A Parent or Legal Guardian of a child under four years of age]
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*621(1) Any Person who is operating a passenger car, Class I truck, Class II truck, classic motor vehicle, antique motor vehicle or motor home registered in Pennsylvania and who transports [such child] a child under four years of age anywhere in the motor vehicle, including the cargo area, shall fasten such child securely in a child passenger restraint system, as defined in subsection (d). This subsection shall apply to all [parents or legal guardians] persons while they are operators or motor vehicles where a seating position is available which is equipped with a seat safety belt or other means to secure the systems or where the seating position was originally equipped with seat safety belts.
(2) Except for children under four years of age and except as provided in paragraph (1), each driver and front seat occupant of a passenger car, Class I truck, Class II truck or motor home operated in this Commonwealth shall wear a properly adjusted and fastened safety seat belt system. A conviction under this paragraph by state or local law enforcement agencies shall occur only as a secondary action when a driver of a motor vehicle has been convicted of any other provision of this title. The driver of a passenger automobile shall secure or cause to be secured in a properly adjusted and fastened safety seat belt system any occupant in the front seat who is four years of age or older and less than 19 years of age....
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(E) Civil actions. — In no event shall a violation or alleged violation of this subchapter be used as evidence in a trial of any civil action; nor shall any jury in a civil action be instructed that any conduct did constitute or could be interpreted by them to constitute a violation of this sub-chapter; nor shall failure to use a child passenger restraint system or safety seat belt system be considered as contributory negligence nor shall failure to use such a system be admissible as evidence in the trial of any civil *622action; nor shall this subchapter impose any legal obligation upon or impute any civil liability whatsoever to an owner, employer, manufacturer, dealer or person engaged in the business or renting or leasing vehicles to the public to equip a vehicle with a child passenger restraint system or to have such child passenger restraint system available whenever their vehicle may be used to transport a child. (Amendments emphasized in the original; deletions bracketed in the original.)
For additional clarification, the term “safety seat belt system” is also defined in Act 82, in Section 1, amending 75 Pa.C.S. § 102:
§ 102. Definitions
Subject to additional definitions contained in subsequent provisions of this title which are applicable to specific provisions of this title, the following words and phrases when used in this title shall have, unless the context clearly indicates otherwise, the meanings given to them in this section:
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“Safety seat belt system. ” Any strap, webbing or similar device designed to secure a person in a motor vehicle in order to mitigate the results of any accident, including buckles, fasteners and all installation hardware as specified by Federal Motor Vehicle Safety Standard No. 209. (Amendments emphasized in the original.)
The import of the amendments is clear: the legislature has decided that a defense of comparative negligence, in the form of a “seat belt defense”, premised on either the failure of an adult to employ a seat belt for his own protection, or on the failure of an adult to employ a seat belt for his own protection, or on the failure of an adult to protect his minor children with seat belts, will not be available in any civil action in this Commonwealth. Section (E) of § 4581 clearly states that the failure to use a “child passenger restraint system” or “safety seat belt system” shall not be considered, in any civil action, as contributory negligence, and shall not be admissible as evidence in any civil action. *623Moreover, the legislature has provided a definition of “safety seat belt system” which includes all known forms of mechanical restraint available, in order to preclude any misconstruction of its intent.
As Section 11 of Act 82 states that the amendments to § 102 and § 4581 “take effect immediately” upon passage of the Act, we conclude that Act 82 of 1987: Act of November 23, 1987 is controlling, and precludes the amendment of appellants’ answer to plead a “seat belt defense” in new matter as comparative negligence. Such amendment is now contrary to a positive rule of law, and cannot be permitted.
Order affirmed.
BECK, J., files a concurring opinion. CAVANAUGH, J. joins BECK, J., concurring opinion as well as the majority.. Contributory negligence and assumption of the risk are affirmative defenses which must be pled in new matter, or are waived. Hence, the trial court’s refusal to permit appellants to amend to plead the comparative negligence of appellees Susan Grim and Gloria Grim, is a final and appealable order. Hughes v. Pron, 286 Pa.Super. 419, 429 A.2d 9, 11 (1981); Grota v. LaBoccetta, 425 Pa. 620, 230 A.2d 206, 207 (1967); Pa.R.C.P. 1030 (as amended December 16, 1983); Goodrich Amram 2d § 1033:8.
. The ownership of the tractor is currently in dispute. It is unclear whether the vehicle was owned by appellant Dallas and Mavis, appellant Freightliner Corporation, or Columbus Truck Center, Inc.
. In the first action, Larry Grim was also a named plaintiff as the administrator of the Estate of Richard Grim.
. It is alleged that PENNDOT was negligent in the design, construction, and maintenance of Route 100, a state-designated highway.
. The trial court did not hold, and appellees do not argue in their brief, that the attempt to amend was in any way untimely or prejudicial. In light of the resolution we reach infra., we needn’t decide whether the requested amendment constituted surprise or prejudice to the plaintiffs.
. We use the qualifier "substantially”, as the state of the law at that time did preclude any attempt to plead Gloria Grim’s negligence in failing to provide a seat belt or child restraint device to protect Richard Grim. Richard Grim died at the age of three, bringing his situation within the confines of the Child Passenger Protection Act, 75 Pa.C.S. §§ 4581-85, as it existed at the time amendment was attempted. That act stated, in relevant part:
§ 4581. Restraint Systems
(a) Child passenger protection. — A parent or legal guardian of a child under four years of age who is operating a passenger car, Class I truck, Class II truck, classic motor vehicle, antique motor vehicle or motor home registered in Pennsylvania and who transports such child anywhere in the motor vehicle, including the cargo areas, shall fasten such child securely in a child passenger restraint system, as defined in subsection (d). This subsection shall apply to all parents or legal guardians while they are operators of motor vehicles where a seating position is available which is equipped with a seat safety belt or other means to secure the systems or where the seating position was originally equipped with seat safety belts.
*620(e) Civil actions. — In no event shall a violation or alleged violation of this subchapter be used as evidence in a trial of any civil action; nor shall any jury in any civil action be instructed that any conduct did constitute or could be interpreted by them to constitute a violation of this subchapter, nor shall failure to use a child passenger restraint system be considered as contributory negligence nor shall failure to use such a system be admissible as evidence in the trial of any civil action; nor shall this subchapter impose any legal obligation upon or impute any civil liability whatsoever to an owner, employer, manufacturer, dealer or person engaged in the business of renting or leasing vehicles to the public to equip a vehicle with a child passenger restraint system or to have such child passenger restraint system available whenever their vehicle may be used to transport a child. (Emphasis supplied).
Hence, conceding that Parise did not preclude a "seat belt defense" as to the adults’ failure to protect themselves through appropriate restraints, and as to their failure to protect their minor children over the age of four through appropriate restraints, we nonetheless find that the state of the law on March 31, 1986, precluded the “seat belt defense" with respect to Gloria’s failure to restrain three year old Richard, under the then-effective provisions of the Child Passenger Protection Act.