to prosecute must be motivated by an impermissible factor remains unclear, however. In Wayte, for example, the Court simply observed that the defendant had to prove that the prosecutor was “motivated by” a discriminatory purpose. See Wayte, 470 U.S. at 608, 105 S.Ct. at 1531. Because of the imprecision of such formulations as “motivated by” and “based upon,” it is uncertain whether the impermissible basis must be: (1) the sole or dominant factor in the charging decision, (2) a lessor “but for” cause of the prosecutor’s selection of the defendant, or (3) only one of a number of reasons, however insignificant, for the prosecutor’s decision. Cf. Village of Arlington Heights v. Metropolitan Housing Development Corp., 429 U.S. 252, 264-68, 97 S.Ct. 555, 562-65, 50 L.Ed.2d 450 (1977) (<HOLDING>). When a selective prosecution defense is
holding that the challenged evidence the government introduced in rebuttal was substantive evidence and not  relevant for impeachment purposes because it was not offered to show that the witness was not a credible person but to show that she was not at the defendants home during the relevant time making her testimony that she did not see any drugrelated activity while at the defendants home irrelevant holding that only relevant factors must be considered holding that the rule 404b evidence admitted to prove intent was clearly relevant because intent was at issue in the trial holding thatplaintiff need not show that challenged action was dominant purpose and including list of evidentiary factors relevant to intent determination holding extraneous acts relevant to show intent in charged offense