delivered the opinion of the Court.
This case is here to review the judgment of the Court of Appeals for the District of Columbia affirming an order of the Subversive Activities Control Board that petitioner register with the Attorney General as a “Communist-action” organization, as required by the Subversive Activities Control Act of 1950, Title I of the Internal Security Act of 1950, 64 Stat. 987. That Act sets forth a comprehensive plan for regulation of “Communist-action” organizations.1 Section 2 of the Act describes a *117world Communist movement directed from abroad and designed to overthrow the Government of the United States by any means available, including violence. Section 7 requires all Communist-action organizations to register as such with the Attorney General. If the Attorney General has reason to believe that an organization, which has not registered, is a Communist-action organization, he is required by § 13 (a) to bring a proceeding to determine that fact before the Subversive Activities Control Board, a five-man board appointed by the President with the advice and consent of the Senate and created for the purpose of holding hearings and making such determinations. Section 13 (e) lays down certain standards for judgment by the Board.
If the Board finds that an organization is a Communist-action organization, it enters an order requiring the organization to register with the Attorney General. § 13 (g). Section 14 provides the right to file a petition for review of Board action in the Court of Appeals for the District of Columbia, with opportunity for review by this Court upon certiorari. Once an organization registers or there is outstanding a final order of the Board requiring it to register, several consequences follow with respect to the *118organization and its members, but these need not now be detailed. See §§ 4, 5, 6, 7, 8, 10, 11, 15, 22, 25.
Proceeding under § 13 (a) of this statute, the Attorney General, on November 22, 1950, petitioned the Board for an order directing petitioner to register pursuant to § 7 of the Act. Petitioner sought unsuccessfully by numerous motions before the Board and by proceedings in the United States District Court for the District of Columbia — one case is reported at 96 F. Supp. 47 — to attack the validity of, and to abort, the hearing. The hearing began on April 23, 1951, before three members of the Board, later reduced to two, sitting as a hearing panel, and it terminated on July 1, 1952. Proposed findings of fact and briefs were filed by both parties, and oral argument was held before the hearing panel in August 1952. In October 1952 the hearing panel issued a recommended decision that the Board order petitioner to register as a Communist-action organization. Exceptions to the panel's findings were filed by both parties, and oral argument was held before the Board in January 1953. The Board filed its report, which occupies 251 pages of the record in this case, on April 20, 1953.
In its report the Board found that there existed a world Communist movement, substantially as described in § 2 of the Act, organized and directed by a foreign government. The Board detailed the history of the Communist Party of the United States and its close relation to the world Communist movement. It then set forth illustrative evidence and made findings with respect to the statutory criteria of § 13 (e) of the Act, which required the Board to consider “the extent to which” the organization met them.2 The Board found that the conditions *119set forth in each of the paragraphs were applicable to petitioner. On the basis of these findings the Board concluded that petitioner was a Communist-action organization, as defined by § 3, and ordered it to register as such with the Attorney General.
Petitioner brought this order to the Court of Appeals for the District of Columbia for review. While the case was pending, it filed a motion, supported by affidavit, *120for leave to adduce additional evidence pursuant to § 14 (a) of the Act.3 The basis of the motion was that the additional material evidence became available to the petitioner subsequent to the administrative proceeding and that this evidence would
“establish that the testimony of three of the witnesses for the Attorney General, on which [the Board] relied extensively and heavily in making findings which are of key importance to the order now under review, was false. ... In summary, this evidence will establish that Crouch, Johnson and Matu-sow, all professional informers heretofore employed by the Department of Justice as witnesses in numerous proceedings, have committed perjury, are completely untrustworthy and should be accorded no credence; that at least two of them are now being investigated for perjury by the Department of Justice, and that because their character as professional perjurors [sic] has now been conclusively and publicly demonstrated, the Attorney General has ceased to employ any of them as witnesses.”
Petitioner listed a number of witnesses whom it proposed to call to substantiate its claim and also set forth a detailed affidavit in support of its allegations.
*121The Government did not deny these allegations. It filed a “Memorandum in Opposition to Motion for Leave to Adduce Additional Evidence,” signed by the General Counsel to the Board and by officials of the Department of Justice. The memorandum asserted that the hearing should not be reopened for the receipt of evidence merely questioning, as it claimed, the credibility of some witnesses, but not any fact at issue, and it maintained that the findings of the Board were amply supported by evidence apart from the testimony of the three witnesses sought to be discredited. On December 23, 1954, this motion was formally denied by the Court of Appeals without opinion. In its full opinion on the merits, filed the same day, however, the Court of Appeals supported its rejection of petitioner’s motion:
“The Party attacks the credibility of the witnesses presented by the Government. In this connection it stresses that some of these witnesses . . . were under charges of false swearing. Full opportunity for cross examination of these witnesses was afforded at the hearing before the Board, and full opportunity was also afforded for the presentation of rebuttal testimony. The evaluation of credibility is primarily a matter for the trier of the facts, and a reviewing court cannot disturb that evaluation unless a manifest error has been made. Moreover the testimony of the witnesses against whom charges are said to have been made was consistent with and supported by masses of other evidence. . . .” 96 U. S. App. D. C. 66, 100, 223 F. 2d 531, 565.
The Court of Appeals affirmed the order of the Board. It sustained § 13 (e) against the contention that its standards were vague and irrational. It held that the findings of the Board had been established by a preponderance of the evidence, except that it struck, as not being *122supported by a preponderance of the evidence, the finding that the secret practices were undertaken for the purpose of promoting the objectives, and concealing the true nature, of petitioner; and it also struck the finding in connection with reporting to a foreign government because the record supported only a finding of reporting by Party leaders “upon occasion,” not a finding which implied a constant, systematic reporting. The court, however, found that the Board’s conclusion was supported by the basic findings which it had affirmed. With respect to petitioner’s other attacks on the constitutional validity of the statute, the court found it necessary to consider some of the so-called “sanction” sections, §§ 5, 6, 10, 11, 22, and 25, as well as § 7, the registration section. It held that they were all constitutional and therefore affirmed the order of the Board.4
The challenge to the Act on which the order was based plainly raises constitutional questions appropriate for this Court’s consideration, and so we brought the case here. 349 U. S. 943. At the threshold we are, however, confronted by a particular claim that the Court of Appeals erred in refusing to return the case to the Board for consideration of the new evidence proffered by petitioner’s motion and affidavit. This non-constitutional issue must be met at the outset, because the case must be decided on a non-constitutional issue, if the record calls for it, without reaching constitutional problems. Peters v. Hobby, 349 U. S. 331.
In considering this non-constitutional issue raised by denial of petitioner’s motion, we must avoid any intima*123tion with respect to the other issues raised by petitioner. We do not so intimate by concluding that the testimony of the three witnesses, against whom the uncontested challenge of perjury was made, was not inconsequential in relation to the issues on which the Board had to pass. No doubt a large part of the record consisted of documentary evidence. However, not only was the human testimony significant but the documentary evidence was also linked to the activities of the petitioner and to the ultimate finding of the Board by human testimony, and such testimony was in part that of these three witnesses. The facts bearing on the issue are not in controversy. The direct testimony of witness Crouch occupied 387 pages of the typewritten transcript; that of Johnson, 163 pages; and that of Matusow, 118 pages. The annotated report of the Board, in which citations to the evidence were made to illustrate the support for its findings, contained 36 references to the testimony of Crouch, 25 references to the testimony of Johnson, and 24 references to the testimony of Matusow. These references were made in support of every finding under the eight criteria of § 13 (e) and it is also not to be assumed that the evidence given by these three witnesses played no role in the Board's findings of fact even when not specifically cited.5 Testimony, for example, directed toward proving *124that the Communist Party of the United States was an agency utilized by a foreign government to undermine the loyalty of the armed forces, and to be in a position to paralyze shipping and prevent transportation of soldiers and war supplies through the Panama Canal, Hawaii, and the ports of San Francisco and New York in time of war, cannot be deemed insignificant in such a determination as that which the Board made in this proceeding.
This is a proceeding under an Act which Congress conceived necessary for “the security of the United States and to the existence of free American institutions . . . .” 64 Stat., at 989. The untainted administration of justice is certainly one of the most cherished aspects of our institutions. Its observance is one of our proudest boasts. This Court is charged with supervisory functions in relation to proceedings in the federal courts. See McNabb v. United States, 318 U. S. 332. Therefore, fastidious regard for the honor of the administration of justice requires the Court to make certain that the doing of justice be made so manifest that only irrational or perverse claims of its disregard can be asserted.
When uncontested challenge is made that a finding of subversive design by petitioner was in part the product of three perjurious witnesses, it does not remove the taint for a reviewing court to find that there is ample innocent testimony to support the Board’s findings. If these witnesses in fact committed perjury in testifying in other cases on subject matter substantially like that of their testimony in the present proceedings, their testimony in this proceeding is inevitably discredited and the Board’s determination must duly take this fact into account. We *125cannot pass upon a record containing such challenged testimony. We find it necessary to dispose of the case on the grounds we do, not in order to avoid a constitutional adjudication but because the fair administration of justice requires it. Since reversal is thus demanded, however, we do not reach the constitutional issues.
The basis for challenging the testimony was not in existence when the proceedings were concluded before the Board. Petitioner should therefore be given leave to make its allegations before the Board in a proceeding under § 14 (a) of the Act. The issue on which the case must be returned to the Board lies within a narrow compass and the Board has ample scope of discretion in passing upon petitioner’s motion. The purpose of this remand, as is its reason, is to make certain that the Board bases its findings upon untainted evidence. To that end it may hold a hearing to ascertain the truth of petitioner’s allegations, and if the testimony of the three witnesses is discredited, it must not leave that testimony part of the record. Alternatively, the Board may choose to assume the truth of petitioner’s allegations and, without further hearing, expunge the testimony of these witnesses from the record. In either event, the Board must then reconsider its original determination in the light of the record as freed from the challenge that now beclouds it.
The case is reversed and remanded for proceedings in conformity with this opinion.
Reversed and remanded.
A “Communist-action” organization is defined in § 3 of the Act as:
“(a) any organization in the United States (other than a diplomatic representative or mission of a foreign government accredited *117as such by the Department of State) which (i) is substantially directed, dominated, or controlled by the foreign government or foreign organization controlling the world Communist movement referred to in section 2 of this title, and (ii) operates primarily to advance the objectives of such world Communist movement as referred to in section 2 of this title; and
“(b) any section, branch, fraction, or cell of any organization defined in subparagraph (a) of this paragraph which has not complied with the registration requirements of this title.” 64 Stat., at 989.
The Act also defines and regulates “Communist-front” organizations, but these sections of the Act are not involved in the present proceeding.
“In determining whether any organization is a ‘Communist-action organization/ the Board shall take into consideration—
“(1) the extent to which its policies are formulated and carried out and its activities performed, pursuant to directives or to effectuate *119the policies of the foreign government or foreign organization in which is vested, or under the domination or control of which is exercised, the direction and control of the world Communist movement referred to in section 2 of this title; and
“ (2) the extent to which its views and policies do not deviate from those of such foreign government or foreign organization; and
“(3) the extent to which it receives financial or other aid, directly or indirectly, from or at the direction of such foreign government or foreign organization; and
“(4) the extent to which it sends members or representatives to any foreign country for instruction or training in the principles, policies, strategy, or tactics of such world Communist movement; and
“(5) the extent to which it reports to such foreign government or foreign organization or to its representatives; and
“(6) the extent to which its principal leaders or a substantial number of its members are subject to or recognize the disciplinary power of such foreign government or foreign organization or its representatives; and
“(7) the extent to which, for the purpose of concealing foreign direction, domination, or control, or of expediting or promoting its objectives, (i) it fails to disclose, or resists efforts to obtain information as to, its membership (by keeping membership lists in code, by instructing members to refuse to acknowledge membership, or by any other method); (ii) its members refuse to acknowledge membership therein; (iii) it fails to disclose, or resists efforts to obtain information as to, records other than membership lists; (iv) its meetings are secret; and (v) it otherwise operates on a secret basis;- and
“(8) the extent to which its principal leaders or a substantial number of its members consider the allegiance they owe to the United States as subordinate to their obligations to such foreign government or foreign organization.” 64 Stat., at 999-1000.
Section 14 (a) of the Act provides:
“. . .If either party shall apply to the court for leave to adduce additional evidence, and shall show to the satisfaction of the court that such additional evidence is material, the court may order such additional evidence to be taken before the Board and to be adduced upon the proceeding in such manner and upon such terms and conditions as to the court may seem proper. The Board may modify its findings as to the facts, by reason of the additional evidence so taken, and it shall file such modified or new findings, which, if supported by the preponderance of the evidence shall be conclusive, and its recommendations, if any, with respect to action in the matter under consideration. . . .” 64 Stat., at 1001-1002.
Judge Bazelon dissented on the ground that the registration provision violated the Fifth Amendment's privilege against self-incrimination because it compelled the person signing it to identify himself as a Communist Party functionary and because it compelled a listing of officers and members. 96 U. S. App. D. C., at 111, 223 F. 2d, at 576.
In this connection the following statement of the Board in its report should be noted:
“In making our findings herein, we have considered and weighed all the evidence of record. In weighing [the Attorney General’s] evidence, we have considered that certain of [his] witnesses fall into the category of ‘informers’ and we have scrutinized their testimony accordingly; we have considered and resolved the inconsistencies in the testimony of certain of [the Attorney General’s] witnesses; we have considered the testimony of [the Attorney General’s] witnesses against the background of their various organizational positions and activities in the CPUSA which afforded the *124sources of their knowledge; and we have had the benefit of the Panel’s observation of their demeanor while testifying. Viewing these considerations in the light of the whole record, we find no basis for disregarding the substance of their testimony.”