guest. His possession of the motel room key and knowledge of the registered occupant’s first name only is insufficient to establish his status as a guest. We find that Conway was without standing to challenge the constitutionality of the search because he failed to demonstrate an actual expectation of privacy and because he failed to demonstrate that he was an invited guest of the registered occupant.
III. The Reasonable Doubt Instruction
The sufficiency of a district court’s jury instructions involves questions of law subject to de novo review. United States v. Barrera-Gonzales, 952 F.2d 1269, 1271 (10th Cir.1992). Conway claims that the court’s instruction defining “reasonable doubt” understated the degree of certainty that a jury must reach in order to find a defendant guilty and subtly shifted the burden of proof to the defense. The challenged instruction stated:
Proof beyond a reasonable doubt is proof that leaves you firmly convinced of the defendant’s guilt. There are very few things in this world that we know with absolute certainty, and in criminal cases the law does not require proof that overcomes every possible doubt. If, based on your consideration of the evidence, you are firmly convinced that the defendant is guilty of the crime charged, you must find him guilty. If on the other hand, you think there is a real possibility that he is not guilty, you must give him the benefit of the doubt, and find him not guilty.
A trial judge retains extensive discretion in tailoring jury instructions, provided that they correctly state the law and fairly and adequately cover the issues presented.
United States v. Merchant, 992 F.2d 1091, 1096 (10th Cir.1993);
United States v. Bryant, 892 F.2d 1466, 1468 (10th Cir.1989),
cert. denied, 496 U.S. 939, 110 S.Ct. 3220, 110 L.Ed.2d 667 (1990). The Supreme Court recognized the breadth of judicial discretion regarding the definition of reasonable doubt in
Victor v. Nebraska:The beyond a reasonable doubt standard is a requirement of due process, but the Constitution neither prohibits trial courts from defining reasonable doubt nor requires them to do so as a matter of course. Indeed, so long as the court instructs the jury on the necessity that the defendant’s guilt be proven beyond a reasonable doubt, the Constitution does not require that any particular form of words be used in advising the jury of the government’s burden of proof. Rather, “taken as a whole, the instructions [must] correctly conve[y] the concept of reasonable doubt to the jury.”
— U.S. -, -, 114 S.Ct. 1239, 1243, 127 L.Ed.2d 583 (1994) (quoting Holland v. United States, 348 U.S. 121, 140, 75 S.Ct. 127, 137-38, 99 L.Ed. 150 (1954)) (bracketed alterations in original) (other citations omitted). Thus, trial courts retain considerable latitude in instructing juries on reasonable doubt.
The instruction challenged in the present case can hardly be described as unusual or untried. It was copied virtually verbatim from the pattern instructions of the Federal Judicial Center. Federal Judicial Center, Pattern Criminal Jury Instructions 17-18 (1987) (instruction 21). Moreover, Justice Ginsburg specifically cited this instruction with approval as a “clear, straightforward, and accurate” explication of reasonable doubt. Victor, — U.S. at -, 114 S.Ct. at 1253 (Ginsburg, J., concurring). We agree that the “firmly convinced” language, juxtaposed with the insistence that a jury must acquit in the presence of “a real possibility” that the defendant is not guilty, is a correct and comprehensible statement of the reasonable doubt standard. Also, we reject the defendant’s contention that the phrase “real possibility,” as opposed to “possibility,” im-permissibly shifts the burden of proof. Barrera-Gonzales, 952 F.2d at 1273.
IV. The Admissibility of the Prior Drug-related Arrests
Conway claims that the district court erred by admitting evidence of his three prior drug-related arrests. He contends that the court’s decision was improper under Rule 404(b) of the Federal Rules of Evidence because the arrests constituted inadmissible character evidence used to demonstrate action in conformity therewith. We review this decision for abuse of discretion.