WILKEY, Circuit Judge.
The defendant Charles C. Diggs, Jr., United States Congressman for the 13th District of Michigan, appeals from a conviction on eleven counts of mail fraud, under 18 U.S.C. § 1341,1 and eighteen counts of making false statements to a United States agency, under 18 U.S.C. § 1001,2 following a [991]*991jury trial before Judge Oliver Gasch of the United States District Court.3 The defendant was sentenced to concurrent terms of incarceration of three years on each count.
The indictment alleged that between T July 1973 and 2 March 1977 the defendant devised a scheme to defraud the United States by misapplying funds allotted for'the compensation of congressional employees.4 On this appeal, the defendant does not challenge the sufficiency of the evidence but contends rather that he lacked the requisite intent to defraud and that he acted within the bounds of his discretion to set the duties and salaries of his congressional employees. For the reasons discussed herein, we reject the defendant’s arguments and affirm his conviction on each of the twenty-nine counts.
I. FACTUAL BACKGROUND
At different periods from October 1973 to January 1977, three of defendant Diggs’ congressional employees — Jean G. Stultz, Felix' R. Matlock, and Ofield Dukes — paid out of the salary allotted to them from the congressional clerk-hire allowance various personal, business, or official expenses of the defendant. That these payments were made is not contested by the defendant; thus a detailed itemization of each of the transactions need not detain us. What is disputed by the defendant are the questions of whether the clerk-hire allowance could be used to defray his congressional expenses5
*and whether the employees’ expenditures were made at his direction.
Congressman Diggs hired Jean G. Stultz in 1972 as a legislative assistant and in the following year promoted her to his personal secretary and staff office manager. In October 1973 Diggs placed Mrs. Stultz on both his personal staff and committee staff payrolls, for which she received two monthly salary checks of approximately $800 and $1,200.6 Although Stultz deposited both paychecks into her own checking account, she allocated the $1,200 monthly check to obligations of the defendant — either personal or congressional ones.7 In August [992]*9921974 defendant removed Stultz from his personal staff payroll and substantially increased the salary she received from the committee staff payroll “almost to a figure to cover the total amount that [she previously received] in the two checks.” 8 From this increase in salary, Stultz continued to pay the defendant’s personal and congressional creditors on a regular basis'.9
Mrs. Stultz testified that in March or April 1976 she informed the defendant that she “no longer wanted to be a part of [it].”10 Her gross annual salary was reduced in April 1976 from $37,355.00 to $22,-700.00.11 The decrease in salary was accompanied by no change in duties.
One fact of importance on this appeal is whether the defendant’s bills were paid “at the direction of Congressman Diggs,” as Mrs. Stultz testified,12 or on Mrs. Stultz’s own volition, as the defendant contends. Mrs. Stultz testified that the defendant approached her with the notion that her salary be increased in order to pay certain of his bills, and that the scheme, after some initial objection on her part,13 was then set into motion: each month she would make a listing of all of the defendant’s accounts, she and the defendant would review this list, and the defendant then would direct her as to which bills were to be paid from the inflated portion of her salary.14 After this decision was reached, Stultz purchased either money orders or cashier’s checks, placed the defendant’s name on these instruments, and mailed them to the defendant’s creditors.15 Defendant Diggs, on the other hand, denied increasing Mrs. Stultz’s salary for the purpose of paying his bills, and he also denied directing her to make these payments. He testified instead that Mrs. Stultz “expressed a willingness” to discharge his obligations.
Felix R. Matlock, one of the defendant’s field representatives in Detroit, also paid expenses of the Congressman from his salary. The bulk of these expenditures were made over an eighteen-month period from September 1975 to January 1977.16 With one minor exception,17 all of these were congressionally related and most were in some way related to the operations of the [993]*993defendant’s district offices in Detroit.18 Corresponding with that time period, the defendant significantly increased Matlock’s salary: Matlock’s annual gross salary jumped from $14,500.00 in July 1975 to $35,-000.00 in September 1975, and to as much as $39,600.00 by the end of 1976.19
Again, the dispute does not center on whether the defendant authorized the increases in Matlock’s salary or whether Mat-lock actually paid the defendant’s district office expenses, but whether the two events were part and parcel of the same scheme, perpetrated by the defendant. Mrs. Stultz testified that Matlock’s salary was increased in order to pay the defendant’s district office expenses, while the defendant denied adjusting Matlock’s salary for this purpose. Both Matlock and Stultz testified that on the defendant’s instructions, Mrs. Stultz advised Matlock which bills were to be paid.20 Consistent with and in confirmation of this, Matlock also asserted that he received orders from the defendant personally following Mrs. Stultz’s resignation in August 1976. Diggs, on the other hand, claimed that he did not instruct Matlock either directly or indirectly on which bills were to be paid.
In December 1976 Matlock stopped making payments toward the defendant’s official expenses.21 In the following month, the defendant reduced Matlock’s gross annual salary from $39,600.00 to $20,000.00 with no apparent change in duties.22
Ofield Dukes, hired in April 1973 as a consultant, paid official expenses of the defendant at various times from June 1973 through January 1976.23 Dukes testified that he received instructions on which bills to pay from Mrs. Stultz and that he was reimbursed for these expenditures through increases in his salary. His base pay of $12,000.00 was raised to as much as $37,-300.00 in November 1975, and finally dropped back to $12,000.00 in February 1976, when Dukes ceased to discharge the defendant’s obligations.24
Finally, the indictment alleges that Jeralee Richmond and George Johnson performed no congressionally related work while they were compensated from the congressional payroll. Defendant placed Jeralee Richmond on the congressional payroll in July 1974 at a salary of $8,500.00. She was employed at the House of Diggs’ Funeral Home in Detroit as a bookkeeper, and she was also expected to deal with problems of constituents who came to the funeral home. Richmond testified that while on the House rolls from July 1974 to August 1976, approximately twenty percent of her time was apportioned to handling constituents’ problems and eighty percent to bookkeeping matters of the funeral home.25 [994]*994The defendant did not dispute her testimony. At no time during this period did Mrs. Richmond receive any compensation from the House of Diggs: her entire salary derived from the congressional clerk-hire funds.26
George Johnson, a certified public accountant in Detroit, was the defendant’s personal accountant and the accountant for the House of Diggs. From July 1973 to December 1974, Johnson received compensation from the congressional clerk-hire allowance. While on the House payroll, Johnson continued to render accounting services to the defendant personally and to the House of Diggs. Defendant does not dispute that fact, asserting, however, that Johnson also aided him in his official capacity. Defendant testified that he hired Johnson as an adviser to draw upon Johnson’s “knowledge and expertise and involvement in the community with respect to black economic development projects.”27 Johnson testified, on the other hand, that he did no “financial or accounting work for Congress” and that he had doubts about receiving compensation from the clerk-hire funds.28 As a result, Johnson quit the congressional payroll in December 1974.29
II. ANALYSIS
The scheme to defraud set forth in the indictment has two subparts: (1) the allegation that the defendant “inflated the salaries of Jean G. Stultz, Felix R. Matlock and Ofield Dukes in order to pay for various personal, business and House of Representatives’ expenses of defendant Diggs,” and (2) the allegation that the defendant placed on the House of Representatives’ payroll Jeralee Richmond and George Johnson “who performed no work for the House of Representatives.” 30 We will consider first that part of the alleged scheme to defraud involving the increases in the salaries of Matlock, Stultz, and Dukes.
A. The Scheme to Defraud: Inflated Salaries of Congressional Employees
1. The Clerk-Hire Allowance
The Government tried its case against the defendant on the rationale that using clerk-hire funds to pay either the Congressman’s personal and business expenses or his official expenses was illegal. The Government combined in the same counts of the indictment transactions relating to both types of expenditures.31 Although defendant admits that it “may have been improper for an employee to be compensated from the clerk-hire allowance for the payment of personal expenses,”32 he asserts that use of the clerk-hire allowance to pay certain of the district office expenses was entirely proper. Thus, putting aside for a moment the question of the defendant’s intent in increasing his employees’ salaries, we must decide in the first instance whether drawing on clerk-hire funds to meet either the defendant’s personal or congressional expenses was illegal. We hold that it was.
The clerk-hire allowance is an appropriation by Congress providing compensation [995]*995“[f]or staff employed by each Member in the discharge of his official and representative duties.”33 On hiring an employee or on adjusting the amount of compensation that an employee will receive, a congressman must submit a “Payroll Authorization Form” to the House of Representatives Office of Finance, marking on the form either the entry entitled “Appointment ” or the one designated “Salary Adjustment.” The obvious reading of this payroll form is that the monies received will accrue to the employees’ sole use and benefit as salary for services rendered. It rules out by implication any other use of the funds.
In Diggs’ case the defendant submitted the payroll forms to the House Office of Finance approving the increases in the salaries of Stultz, Matlock, and Dukes with the knowledge,34 undeniable after the first remittitur, that the increment would be used to pay his personal and official expenses. These payments benefited not the employees but the defendant himself. Obviously the defendant directly benefited from the payments to his personal creditors and to the creditors of his business, the House of Diggs. It is equally clear that the defendant profited from the payment of his congressional expenses. Payment of these bills enabled the defendant to provide services to his constituents and thus furthered his prospects for reelection.35
Defendant argues nevertheless that using clerk-hire funds to compensate employees for paying district office expenses fell within his discretion to determine both the salaries and responsibilities of his employees, provided those responsibilities relate to the Congressman’s “official and representative duties.”36 The phrase “official and representative duties,” so the argument goes, is sufficiently broad to encompass an employee’s responsibility for paying congressional expenses.37 We disagree.
The defendant's argument erroneously equates a congressman’s discretion to define the duties of an employee with the unfettered power to divert monies intended for one purpose to another, completely unauthorized purpose. During the period relevant to the indictment, the Committee on House Administration had fixed an allowance for district office expenses at $500 per quarter or $2,000 per annum.38 Thus the allowance for clerk-hire and the allowance for district office expenses were separate and distinct.39 No House regulation or order authorized the commingling of these funds, either directly, or, as in this case, [996]*996indirectly.40 Had Congress intended that the clerk-hire funds be used to pay expenses of the district office it could have so provided.41
After the events relevant to the defendant’s conviction had already taken place, the House Administration Committee published Committee Order No. 30 (Transfer Among Allowance), effective 3 January 1977.42 Committee Order No. 30 permits the transfer of up to $15,000 from the clerk-hire allowance to two other funds, from which allocation then may be made to cover other expenditures, including “Official Expenses Outside the District of Columbia.” The order has no retroactive effect.43 Adoption of the order to permit the transfers here at issue thus strongly suggests that this practice was not permitted prior to the effective date of the order. Even if the order were retroactive, it would not justify the defendant’s conduct in this instance. A congressman may transfer funds from the clerk-hire allowance to the allowance for official expenses provided he certifies to the House Office of Finance of his election to do so.44 Diggs certified the opposite. If the new order had been in effect, Diggs made false statements- even by that standard.
In defense, Diggs cites the testimony of the Chief of the House Office of Finance, [997]*997Mr. John Lawler, for the notion that- the clerk-hire funds could be applied to district office expenses. When questioned by the prosecutor regarding the purpose of the clerk-hire allowance, Mr. Lawler testified:
It’s used to pay compensation of employees in the performance of official duties.45
When pressed further on whether the allowance “include[d] any expenses which were incidental to the employment,” Mr. Lawler responded:
The regulations in that time period didn’t have any specific definition as far as official duties. It’s silent on the question of what it might include.46
Rather than providing support for the defendant’s position, Mr. Lawler’s rather cautious testimony can be taken to do no more than state the obvious: it was within a congressman’s discretion to define the parameters of an employee’s responsibilities so long as those responsibilities related to the congressman’s “official and representative duties.” Lawler’s testimony cannot be interpreted to mean that a congressman also had the discretion, under the guise of compensating his employees, to appropriate clerk-hire funds for purposes other than those intended by the appropriation and duly certified by the congressman.
2. Mail Fraud
With these conclusions in mind, we turn now to the law applicable to the mail fraud and false statements statutes.47 The basic elements of the offense of mail fraud under 18 U.S.C. § 1341 are “(1) a scheme to defraud, and (2) the mailing of a letter, etc., for the purpose of executing the scheme.” 48 Because only “a scheme to defraud” and not actual fraud is required, proof of fraudulent intent is critical.49
In this case, the testimony concerning the defendant’s intent was conflicting. Briefly recalling the evidence, the key witness for the Government, Jean G. Stultz, testified that the defendant increased her salary and the salaries of Felix Matlock and Ofield Dukes for the purpose of using the inflated portions to pay the defendant’s expenses. Mrs. Stultz also asseverated that the payments she made “were always ... at the direction of Congressman Diggs.”50 The defendant’s testimony essentially was that Jean Stultz voluntarily paid his bills to ease his financial situation. Far from being voluntary, Stultz testified that she “felt that it was almost — you might almost say a condition of employment.”51
Stultz also claimed that the defendant directed her to instruct Matlock and Dukes on which district office expenses to pay from their inflated salaries. Matlock and Dukes both corroborated the fact that Stultz directed them to make these payments, and Matlock further asserted that he received his instructions from the defendant personally after Mrs. Stultz resigned in August 1976. He added that he went along with the scheme only because he “didn’t want to make any waves.”52 While the défendant admitted that Dukes and Mat-lock paid certain congressional expenses,-he disclaimed any intention of inflating their salaries for this purpose. This was the is[998]*998sue the defendant’s own testimony made in regard to his intent.
It was entirely within the province of the jury to resolve the conflicting testimony. The jury concluded that the defendant personally devised and directed a scheme to divert portions of the three employees’ salaries to meet his personal and official expenses. We hold that there was ample evidence to support this conclusion.
Second, we find that the actual scheme to defraud has clearly been established. No House regulation or order authorized the use of the clerk-hire allowance for purposes other than the sole use and benefit of the staff of a congressman; the money was to go to individual employees for their personal salaries and subsequent personal use or it was not to be expended at all. Defendant submitted payroll authorization forms to the House Office of Finance approving the increases in his employees’ salaries while concealing the fact that these monies would be diverted to the Congressman’s own benefit. His conduct amounted to no less than a scheme to take illicit kickbacks from his employees in the form of payments of his personal or congressional expenses.
The courts have held that kickback schemes involving the use of the mails run afoul of the mail fraud statute:
[T]he mail fraud statute is violated when some or all of the following factors are present: a duty to disclose an interest with a concomitant failure to do so; an attempt to cover-up through false pretenses; a taking of money or property or rights of another through the use of kickbacks, extortion, bribery, tax evasion, perjury, or violation of some state or federal statute; a use of the United States mails.53
The defendant defrauded the public of not only substantial sums of money but of his faithful and honest services.54
The final element under the mail fraud statute is a use of the United States mails ‘“for the purpose of - executing the scheme.’ ”55 One must “cause” the mails to be used to satisfy this requirement. In Pereira v. United States the Court held that a defendant “causes” the use of the mails where he “does an act with knowledge that the use of the mails will follow in the ordinary course of business, or where such use can reasonably be foreseen, even though not actually intended.”56 In addition, although the schemer need not “contemplate the use of the mails as an essential element,”57 the mailings must be “sufficiently closely related to [the] scheme to bring his conduct within the statute.”58
Applying these principles to the case at bar, we hold that the mailings were reasonably foreseeable and were sufficiently closely related to the defendant’s scheme to bring his conduct within the coverage of 18 U.S.C. § 1341. The paychecks were mailed to Felix Matlock from Washington, D.C., to Detroit, Michigan. It was “reasonably foreseeable” that Matlock would receive these checks via the United States mails by [999]*999virtue of the simple fact that Matlock lived and worked in Detroit. That the checks somehow could have been delivered otherwise than through the mails is immaterial.59 Moreover, a sufficiently close nexus existed between the fraudulent scheme and the mailings of the checks. The checks contained the actual proceeds of the fraud and thus constituted the “lifeblood of the scheme” from the defendant’s viewpoint.60 Manifestly, these mailings were in furtherance of the scheme to defraud.
3. False Statements
Having concluded that the defendant violated the mail fraud statute, we address the question of whether the defendant was also guilty of transgressing 18 U.S.C. § 1001. The courts have interpreted, section 1001 to require that the false representations made to the “department or agency” be material.61 The test of materiality is whether the statement “has a natural tendency to influence, or was capable of influencing, the decision of the tribunal in making a [particular] determination.” 62 Proof of actual reliance on the statement is not required; the Government need only make a reasonable showing of its potential effects.63
In this case, the defendant was accused of falsifying the payroll authorization forms submitted to the House of Representatives Office of Finance for his employees Stultz, Matlock, and Dukes.64 In seeking the payroll increases for these employees, Congressman Diggs failed to disclose to the Office of Finance the real purpose for which the monies were intended — the defrayal of his personal and congressional expenses. Had the defendant revealed these intentions, it reasonably could be expected that the Office of Finance would not have honored the payroll requests or at least would have referred the matter to the appropriate House committee for advice.65 We hold, therefore, that the defendant’s omissions were material.66
4. Jury Instructions
The defendant assigns as error part of an instruction that the trial judge gave to the [1000]*1000jury for both the mail fraud and false statement offenses on the question of the defendant’s intent:
The question is whether the defendant at the time he approved the payroll authorizations representing that certain employees would be paid specific salaries intended that those employees would actually receive and have the complete use of those salaries, or did he intend that a portion of the salary would be remitted by the employee for the payment of his obligations. What I have said respecting good faith as a defense in a mail fraud charge is also applicable to false official statement charges.67
The defendant claims that the instruction deprived him of his good faith defense and erroneously directed the jury, as a matter of law, that diverting employees’ salaries for payment of congressional expenses was unlawful. The defendant’s contentions are without merit.
The charge to the jury must be considered in two parts. The first aspect of the charge concerns the defendant’s intent at the time he approved the adjustments in the salaries of his employees. This part does no more than pose the question of good faith exactly as the defendant himself had presented the issue at trial. The defendant denied ever having increased the salaries of his employees with the intention of using the excess to pay his bills; the testimony of his employees was uniformly to the contrary. The defendant claimed they volunteered the money; the employees said payment to Diggs of part of their inflated salaries was virtually a condition of employment. The employees also pointed to the remarkable rise in their salaries when they began payments to or for Diggs, and the immediate drastic reduction when each ceased being a part of the scheme. The trial judge properly called upon the jury to resolve this issue. Viewing the disputed portion of the instruction in connection with the whole charge, we find that the instruction correctly informed the jury on the question of the defendant’s good faith.
The second aspect of the instruction involves the propriety of combining under the term “obligations” not only the payments of the defendant’s personal and business expenses but the payments of his congressional expenses as well. We need not reiterate the reasons for our conclusion that diverting employees’ salaries to meet either the defendant’s personal or official expenses was unlawful. The judge merely combined under one heading two kinds of illegal payments; he was not required to deal with each separately in the instruction. We hold that no error may be attributed to the instruction.
5. House Committee Advisory Opinion
Defendant also claims that the Government predicated its theory of prose[1001]*1001cution of the alleged violations on an advisory opinion of the House of Representatives, thus unconstitutionally casting this court into the role of interpreting the internal rules of the House.68 The advisory opinion, issued by the Committee on Standards of Official Conduct of the House of Representatives, suggests that “it is improper to levy, as a condition of employment, any responsibility on any clerk to incur personal expenditures for the primary benefit of the Member or of the Member’s congressional office operations.”69
The defendant confuses the purpose for which the advisory opinion was introduced in evidence and thus misconceives our role. The opinion was admitted as evidence relevant to the defendant’s intent, and not as a legal standard to which the defendant’s conduct was required to conform. The defendant testified that he believed an employee properly could “make available . . . funds from [his] salary” to pay his expenses.70 The opinion had some bearing on the defendant’s belief or intent. It was permissible to introduce it into evidence to rebut the defendant’s testimony.
The defendant clearly was tried not for violating the internal rules of the House of Representatives but for violating the mail fraud and false statements statutes. As the Supreme Court held in United States v. Brewster,71 a member of Congress may be prosecuted under a criminal statute provided the government’s case does not intrude into legislative processes or functions. No such improper probing is alleged in this case. Article I, § 5 does not immunize a member of Congress from the operations of the criminal laws.72 As the Supreme Court has stated:
No man in this country is so high that he is above the law. No officer of the law may set that law at defiance with impunity. All the officers of the government, from the highest to the lowest, are creatures of the law, and are bound to obey it.
It is the only supreme power in our system of government, and every man who by accepting office participates in its functions is only the more strongly bound to submit to that supremacy, and to observe the limitations which it imposes upon the exercise of the authority which it gives.73
B. The Scheme to Defraud: Salaries for Noncongressional Employees
Having concluded that the defendant engaged in a scheme to defraud the government by inflating the salaries of Matlock, Dukes, and Stultz, it remains to be considered whether the defendant also schemed to defraud the government, in violation of 18 U.S.C. §§ 1001 and 1341, by placing on the House of Representatives’ payroll Jeralee Richmond and George Johnson. Summarizing the evidence, the defendant acknowledged that George Johnson, a certified public accountant, provided [1002]*1002personal services while on the House rolls from July 1973 to December 1974 but claimed that Johnson also acted as an adviser to him “with respect to black economic, development projects.”74 Johnson testified, in contrast, that the defendant and the House of Diggs were indebted to him, and that once the defendant placed Johnson on the congressional payroll he told Johnson to “go ahead and adjust these checks [Johnson’s paychecks] against the bills.” 75 Johnson also asserted that he “didn’t at least do any . . . financial or accounting work for Congress.”76 He quit the congressional payroll in December 1974 because he “just couldn’t rationalize receiving those checks.”77
Jeralee Richmond, employed at the House of Diggs’ Funeral Home, allocated approximately eighty percent of her time to bookkeeping work and only twenty percent to handling constituents’ problems. From July 1974 to August 1976, however, she received her entire compensation from the congressional clerk-hire allowance.
1. False Statements
The defendant argues that Richmond and Johnson properly were compensated from the clerk-hire allowance because they both had official responsibilities. It was a matter of his discretion to fix their duties and salaries as congressional employees,78 and the fact that these employees concededly rendered personal services as well, he claims, did not affect the exercise of that discretion. His failure to reveal the exact nature of the employees’ responsibilities on the payroll forms submitted to the House Office of Finance is thus contended to be immaterial.
We find the defendant’s argument without merit. This case presents a situation analogous to that confronted in Bramblett v. United States79 In that case, a former United States Congressman devised a scheme to convert to his own use monies allotted for the payment of congressional employees. The defendant was convicted of violating 18 U.S.C. § 1001 by falsely and fraudulently representing to the disbursing office of the House of Representatives that a named individual was entitled to compensation as his official clerk, when that individual in fact did no congressional work.80
We see no significant difference between Bramblett in which the employee performed no congressionally related work while on the congressional payroll and this case in which only a nominal percentage of Richmond’s and Johnson’s responsibilities were congressionally related. The difference is merely one of degree and not of substance. There was sufficient evidence from which the jury could conclude that the defendant in fact placed Richmond and Johnson on the payroll with the intention of compensating them for services rendered to the House of Diggs or the defendant. The defendant’s representations to the House Office of Finance that Johnson and Richmond were bona fide congressional employees therefore were fraudulent and material, in violation of 18 U.S.C. § 1001.
We also are of the opinion that the mail fraud violations were proven. First, there is sufficient evidence from which to infer the defendant’s fraudulent intent as the perpetrator of the scheme to defraud: [1003]*1003to reiterate, the jury reasonably could have concluded from all the evidence that the defendant placed Johnson and Richmond on the payroll in order to compensate them for services rendered to himself and his business. Second, the requirement of a use of the mails was also satisfied. The paychecks were mailed to Richmond and Johnson in Detroit, Michigan, from Washington, D.C. That the United States mails would be used to deliver these paychecks clearly was foreseeable.81 The mailings were also sufficiently related to the scheme to satisfy the-requirement that they be “ for the purpose of executing the scheme. ”82 The paychecks contained the actual proceeds of the fraudulent scheme.83 Their delivery thus was in furtherance of the scheme to defraud.
C. Selective Prosecution
Finally, the defendant claims as error the trial court’s failure to grant the defendant’s motion for discovery and an evidentiary hearing on his allegation of selective prosecution.84 We find that the defendant’s claim has no merit.
The conscious exercise of some selectivity in prosecuting individuals for similar conduct is permissible.85 To establish a prima facie case of discriminatory or selective prosecution, a defendant must show that “ ‘the selection [is] deliberately based upon an unjustifiable standard such as race, religion, or other arbitrary classification.’ ”86
That burden has not been met in this case.87 As a preliminary matter, we note that the defendant has not demonstrated to our satisfaction that he was singled out for prosecution. The defendant sought discovery of the Government’s reasons not to prosecute three other congressmen who allegedly had engaged in conduct similar to that forming the basis of the charges against the defendant.88 One of the three, Congressman James Hastings, however, in fact was prosecuted and convicted for taking kickbacks from employees to pay his personal bills.89
Even assuming that the defendant’s evidence of selective enforcement somehow was sufficient, he has not shown that the decision to prosecute was based on an unjustifiable standard. All that the defendant could point to in support of his claim was the general danger that the selective prosecution of congressmen for actions relating to their official responsibilities could “ ‘become a weapon used to discipline politi[1004]*1004cal foe[s].’ ”90 While a concern for the integrity of the legislative process prompts careful inquiry into a congressman’s claim of discriminatory prosecution,91 there must be at least some substance to that contention. Defendant made no colorable showing whatsoever that he was prosecuted for improper political purposes.92
III. CONCLUSION
In conclusion, we hold that the case was proved and the conviction is
Affirmed.