(dissenting, with whom Cowin, J., joins). In Commonwealth v. Bernardo B., 453 Mass. 158 (2009) (Bernardo B.), four juveniles, all under sixteen, the age of legal consent, were alleged to have been engaged in consensual sexual activity. Three of the juveniles were girls and one was a boy. In spite of efforts by the boy’s counsel to ensure that delinquency complaints were brought against the females for the sexual conduct they engaged in with his client, the prosecutor determined to charge only the boy for the sexual conduct.
After acknowledging the broad discretion afforded the Commonwealth in deciding to prosecute one case over another (resting as it does on the constitutional doctrine of separation of powers), the court concluded that the facts of the case on their face provided sufficient support to a claim of selective prosecution based on an impermissible ground (gender) to warrant the award of discretionary discovery from the prosecutor regarding “data concerning the gender of complainants and accuseds under the age of sixteen in cases in Plymouth County concerning charges identical to certain charges brought against the boy.” Id. at 174. As the court explained, “the question here is whether [the boy’s] behavior was so dissimilar from that of the girls in nature, kind, and degree as to nullify the possibility that *150his discovery request might yield information relevant to a claim of selective prosecution.” Id. at 173. The court answered the question in the negative, and thus concluded that the single justice did not abuse her discretion in upholding the Juvenile Court judge’s order.
The case before us bears little resemblance to the facts and circumstances the court faced in Bernardo B. The juvenile in this case stands in very different shoes than the juvenile in Bernardo B., and the grounds for his prosecution, already presumed regular and permissible, are particularly strong. While the complainant was thirteen years of age at the time of the four alleged sexual assaults, the juvenile was sixteen and over the age of consent at the time he is alleged to have raped the complainant on two occasions, and sexually assaulted him on a third. As the court noted in Bernardo B., the age of consent is an important line in the law, intentionally laid down by the Legislature “to protect all children under sixteen years old from sexual abuse.” Id. at 171. In other words, this is not a case about decision-making regarding identically situated children, raising on its very face a plausible question of selective prosecution. Absent some additional showing that the “discovery request might yield information relevant to a claim of selective prosecution,” id. at 173, the answer to the question posed by the court in Bernardo B. is, in this case, “yes,” the sexual behavior of someone over the age of sixteen directed at someone significantly below that age is sufficiently dissimilar to nullify the possibility that discovery will yield the type of information sought.
Moreover, in direct contrast to the facially plausible claims in Bernardo B., the juvenile has made no showing whatsoever that selective prosecution may have occurred in this case. At most, he urges an order of discretionary discovery on the ground that it might result in evidence of his selection for prosecution based on impermissible criteria. Surely, claims for discretionary discovery of this type require some support: a threshold showing of plausibility beyond rank speculation. Id. at 174 (request for discovery “must be properly supported”). Yet here there is no showing at all. As the court itself admits, “[djespite the lack of a threshold showing based on the evidence presented by the juvenile ... the juvenile’s claim is sufficiently serious to warrant further inquiry.” Ante at 147. Contrast Bernardo B., supra *151at 173 (juvenile “has made a threshold showing based on credible evidence that he is entitled to discovery” concerning claim of selective prosecution).
The result of this case is a regime where any claim of selective prosecution made in a juvenile case may warrant intrusions into the decision-making powers delegated to another branch of government — no matter how far fetched or unsupported — on the hope that something of statistical significance might emerge. Based on the rationale used by the court, there always might be, at least hypothetically, some evidence to support a statistical claim of selective prosecution in the confidential files of the Juvenile Court, if only the accused could get access to it. Because he cannot access those files directly, the court has concluded that the burden should be placed on the prosecutor to compile and provide that information to him. This articulated justification is unbounded.
In sum, the order entered by the Juvenile Court judge was an abuse of discretion, and the grounds on which it has been affirmed represent a misapplication of our jurisprudence with significant implications for baseless and systematic intrusions into the exercise of constitutional powers that reside in another branch.
I respectfully dissent.