Following a jury trial, defendant-appellant Jose Manuel de la Cruz was found guilty on two counts of unlawfully transporting undocumented aliens, 8 U.S.C. § 1324(a)(1)(B), and two counts of unlawfully harboring undocumented aliens, 8 U.S.C. § 1324(a)(1)(C). Represented by new counsel, he prosecutes this appeal.
I.
We need not linger long over appellant’s claims of mid-trial error. He contends that the district court erred, first, in not giving more carefully defined instructions to the jury; and second, in admitting evidence of appellant’s earlier conviction for a near-identical offense. Neither contention has merit.
A.
As to the claimed instructional error, the short answer is that appellant’s trial counsel did not object to the charge as given. That being so, we review the supposedly defective charge only for “plain error.”
See United States v. Boylan,
*123
The appellant does not complain that the charge given was incorrect, but rather that certain terms comprising (or touching upon) elements of the tried offenses could — and should — have been more explicitly defined. Appellant points particularly to three largely undefined phrases: “harboring,” “transporting,” and “reckless disregard.” Considering the charge “as a whole,”
see United States v. Cintolo,
In the context of this case, the jury could not reasonably have doubted the tenor of verbs such as “harboring” and “transporting.” And while it may have been better practice to define “reckless disregard” — a matter as to which we take no view — we do not think it was necessary for the district court to venture forth in the absence of a specific request.
See
Fed.R.Crim.P. 30.
Cf., e.g., United States v. Littlefield,
B.
Appellant’s assignment of evidentiary error has three prongs. It is thrice unavailing. The basic “error” stems from the district court’s admission of evidence that in 1985, some two years before the instant offenses were allegedly committed, appellant was charged with, and convicted of, a nearly identical felony.
Appellant’s initial claim — that the evidence was bereft of probative value — is vapid. Given defendant’s assertion that he lacked knowledge of the aliens’ undocumented status, we think that proof of the prior conviction was highly probative under Fed.R.Evid. 404(b) (evidence of other crimes admissible to prove, inter alia, “intent, ... plan, knowledge ... or absence of mistake”). In other words, the evidence had a “ ‘special’ probative value ... to prove some controverted issue in the case.”
United States v. Rodriguez-Estrada,
Appellant’s second claim is itself dichotomous. He says that the evidence’s prejudicial effect outweighed its probative value and that the lower court failed to make needed findings in this regard. Whether taken separately or in the ensemble, these protests fizzle.
To be sure, the admission of Rule 404(b) evidence is restricted by Fed.R.Evid. 403 (relevant evidence excludable “if its probative value is substantially outweighed by the danger of unfair prejudice”); and Rule 609(a)(1) contains an internalized balancing test which is somewhat stricter (prior conviction not admissible unless “probative value of admitting this evidence outweighs its prejudicial effect to the defendant”). When these rules are in play, it is certainly good practice for the trier to make on-the-record findings as to the probative value/prejudicial effect balance. That was not done here.
1
Yet, explicit findings need not always be made.
See, e.g., United States v. Foley,
For practical purposes, that settles the issue. We have repeatedly recognized the considerable extent to which such balancing “determinations are committed to the trial court’s sound discretion.”
Rodriguez-Estrada,
Appellant’s parting shot at this evidence castigates the district court for its failure to give a limiting instruction when the earlier conviction surfaced. But, appellant never asked for such an instruction. The general rule is that “the failure of the trial court to give [a cautionary instruction]
sua sponte
is not reversible
error.” United States v. Rivera-Santiago,
II.
The remaining ground of appeal is much more problematic. We are told that the jury which convicted de la Cruz was empaneled not by the district judge, but by a magistrate. Long after that event, the Supreme Court ruled that the Federal Magistrates Act did not empower a magistrate to preside over empanelment in a felony trial.
See United States v. Gomez,
— U.S. -,
In
Gomez,
a case arising from another circuit, the defendants had seasonably objected to empanelment by the magistrate.
Id.
Given the uncertain state of the law, as well as the absence of even the most rudimentary record concerning how the empan-elment in this case came about (we find ourselves without so much as a transcript of the empanelment itself), we believe that *125 prudence suggests we decline appellants invitation to rule in a vacuum. We therefore leave the issue undecided and remand to the court below. The district court should await our opinion en banc, in the case just mentioned, and then develop the record as to what transpired at and in the course of the empanelment. It should thereafter proceed in accordance with the en banc opinion, providing a new trial if required.
We affirm the judgment of conviction in all respects subject to resolution of appellant’s contention that the manner of jury empanelment requires a new trial. As to that facet of the matter, we remand to the district court for further proceedings consonant herewith. So ordered.
Notes
. Despite the lack of express findings, we believe that the record reflects the district court’s awareness of its responsibility to weigh the relevant factors and perform a balancing test prior to allowing the government to use the disputed evidence. See, e.g., Trial Transcript at p. 205 (discussion at sidebar).
. The original panel decision involved six consolidated cases (No. 87-2003 through No. 87-2008) and was reported sub nom. United States v. Lopez-Pena. Only three of the defendants petitioned for rehearing en banc. The petition was granted on February 9, 1990 sub nom. United States v. Martinez-Torres.
