Rosario, became a key witness against him — a witness whose testimony constituted the cornerstone of the government’s case.
The matter was tried twice. On the first occasion, the jury found Paniagua guilty on the conspiracy count but acquitted him on a related charge. The trial judge voided the conviction, however, based on what he retrospectively found to be prejudicial error in the jury instructions. The government unsuccessfully appealed the order granting a new trial. See United States v. Paniagua-Ramos, 135 F.3d 193 (1st Cir.1998).
Upon retrial, the jury returned a verdict on August 25, 1998. It again found Pan-iagua guilty of conspiracy.
On March 10, 1999, the court sentenced Paniagua to serve a 235-month incarcera-tive term. Paniagua appealed. He later moved for a new trial on the ground of jury taint. When the district court rebuffed this effort, a second appeal ensued.2 By order dated June 15, 2000, we consolidated the two appeals for briefing, argument, and adjudication.
II
Paniagua’s first claim of error involves the lower court’s jury instructions. He calumnizes the testimony of the turncoat witness, del Rosario, and argues that the court erred in failing sufficiently to emphasize that the jurors should have received this testimony with caution and scrutinized it with care. He adds that the court compounded this error by failing to instruct the jurors that they should not convict on the unsupported testimony of an accomplice absent a belief “beyond a reasonable doubt that the accomplice is telling the truth.” United States v. Dailey, 759 F.2d 192, 200 n. 8 (1st Cir.1985). This claim lacks force.
We do not gainsay the obvious: courts long have recognized the special “pitfalls that accompany accomplice testimony. In an appropriate case, a criminal defendant is entitled, upon timely request, to an instruction that calls the jury’s attention to these dangers. E.g., United States v. Pelletier, 845 F.2d 1126, 1129 (1st Cir.1988). There are, however, no magic words that must be spoken in this regard.
This is as it should be. The primary function of a trial court’s instructions is to create a roadmap for the jurors, limning those legal rules that they must follow in finding the facts and determining the issues in a given case. For the most part, the law provides no set formulae for converting these legal rules into lay language — and the choice of what words are to be spoken belongs, within wide margins, to the trial judge. See United States v. Houlihan, 92 F.3d 1271, 1299 n. 31 (1st Cir.1996) (remarking the trial court’s “broad discretion to formulate jury instructions as it sees fit”); United States v. Nivica, 887 F.2d 1110, 1124 (1st Cir.1989) (noting that the trial judge need not parrot proffered instructions).
It also bears mention that the formulation of jury instructions in a criminal case is an interactive process. The trial judge must, of course, pull the laboring oar — but the parties have a corollary responsibility seasonably to apprise the judge about what they think the jury should or should not be told. See Fed.
2
In United States v. Josleyn, 206 F.3d 144, 150-51 (1st Cir.2000), we left open the question of whether a defendant in a criminal case needs to file a separate notice of appeal from an order denying a post-sentence motion for new trial (or, conversely, whether the original notice of appeal from the judgment of conviction suffices to bring that order before the appellate court). This case does not require us to answer that question.