Three civil cases commenced pursuant to G. L. c. 272, § 30, in different counties, were consolidated and tried before a judge in the Superior Court, Middlesex County. The plaintiffs, district attorneys, each alleged that a corporate defendant was exhibiting obscene motion pictures and requested injunctive relief. The trial judge viewed the films alleged to be obscene and heard expert testimony offered by the plaintiffs and the defendants. In response to the defendants’ claims for a jury trial, he ruled that injunctive proceedings under G. L. c. 272, S 30, did not entitle either party to a jury trial as matter of right. The judge then applied the Miller test, Miller v. California, 413 U.S. 15, 24 (1973), as incorporated into G. L. c. 272, § 31, see Commonwealth v. 707 Main Corp., ante, 374, 376 n.1 (1976), decided today, and found that the films lacked any serious literary, artistic, political or scientific value and that they appealed to prurient interest. However, he found that the plaintiffs had failed to show by a preponderance of credible evidence that the films depicted sexual conduct in a patently offensive way and ruled the films not “obscene” within the definition set forth by G. L. c. 272, § 31. In reaching this conclusion he ruled that expert testimony is required concerning the type of matter that would offend the average person in Massachusetts.

*393The plaintiffs appealed from the dismissal of their complaints, alleging prejudicial error in the requirement that they present expert testimony in order to prove that the films’ depictions were patently offensive. They also claim that the judge’s finding that the films did not depict sexual conduct in a patently offensive way was clearly erroneous. The defendants, on cross appeal, claim that G. L. c. 272, §¡5 28C-32, violate the equal protection provisions of the United States Constitution because they grant a jury trial to defendants in H 28C-28I proceedings which are required only for prosecution of books, but deny a jury trial to defendants in § 30 proceedings which constitute the only civil proceedings available against other materials, including films. The defendants also claim that the statutes violate the due process provisions of the United States and Massachusetts Constitutions.

We conclude that the judge erred in requiring expert testimony on the issue of “patently offensive” depictions of sexual conduct. We further conclude that G. L. c. 272, §§ 28C-31, do not violate the equal protection or due process provisions of the United States or Massachusetts Constitutions facially or as applied to these cases. Commonwealth v. 707 Main Corp., supra, 374, and Commonwealth v. Thureson, ante, 387 (1976), decided today.

1. The parties to these cases do not contest the judge’s finding that the motion pictures alleged to be obscene contain depictions of “sexual conduct” within the definition of G. L. c. 272, § 31. We hold today that this statutory definition includes only “hard core” sexual conduct as described in Miller v. California, 413 U.S. 15, 25 (1973), and Jenkins v. Georgia, 418 U.S. 153, 160 (1974). Thus, the trier of fact could constitutionally find the films to be “patently offensive,” Jenkins, supra at 161, and, once the films themselves were placed in evidence, the plaintiffs had presented a prima facie case on this issue. Kaplan v. California, 413 U.S. 115, 121 (1973). Paris Adult Theatre I v. Slaton, 413 U.S. 49, 56 (1973).

The judge nevertheless found that the plaintiffs failed to meet their burden of proof on the issue of patent offen*394siveness, concluding that he could not, as the trier of fact, decide whether the average citizen of Massachusetts today would think the films were “patently offensive.” He was incorrect. There is no constitutional requirement that the prosecution offer expert testimony on the issue of obscenity itself or any ancillary issue. Kaplan, supra at 121. Moreover, the trier of fact may draw on his own knowledge of normative views in his own community in applying statutorily prescribed community standards. Hamling v. United States, 418 U.S. 87, 104 (1974). The “contemporary community standard” functions to bar use of personal views or a peculiar group as a measure of obscenity. Id. at 106. Thus, the judge in these cases, disregarding his own views on the offensiveness of the films in question, could use his own knowledge of normative sensibilities to hard core depictions of sexual conduct in this Commonwealth in deciding whether the films were “patently offensive” within the statutory concept.

Because the judge below incorrectly required expert testimony on the subject of community standards for proof of obscenity, the complaints were dismissed improperly. The judgment therefore must be reversed and the cases remanded for further proceedings consistent with this opinion.

2. We decided today that G. L. c. 272, 28C-31, are facially constitutional. Commonwealth v. 707 Main Corp., supra. The definitions of “obscene” matter and “knowledge” are neither vague nor overbroad and give adequate notice of proscribed conduct to potential defendants and law enforcement officials. The disparity of procedural protection afforded books and other matter through 28C-281 may be rationally justified and is therefore constitutionally permissible.1 In addition, the denial of a right to jury trial in § 30 injunctive proceedings, itself constitutionally permissible (see Alexander v. Virginia, 413 U.S. *395836 [1973]), does not deny S 30 defendants equal protection of the law. Indeed, denial of a jury right is critical to the constitutionality of injunctive proceedings such as those established by § 30, since speedy final adjudications are required to avoid restraint of a mode of expression which may be constitutionally protected. Freedman v. Maryland, 380 U.S. 51, 59 (1965). Speed is not constitutionally necessary for in rem proceedings such as'those established by §§ 28C-28I. Hence, the statutory grant to 5S 28C-28I defendants and denial to S 30 defendants of a jury right both has a rational basis and performs a protective function by providing for jury fact-finding whenever constitutionally possible in the area of obscenity adjudication.

For the above reasons, the judgment in these cases is reversed and the cases are remanded to the Superior Court for proceedings not inconsistent with this opinion.

So ordered.

dissenting, refers to his dissenting opinion in Commonwealth v. 707 Main Corp., ante, 374, 386 (1976), decided this day.