dissenting.
In my view, petitioners, all indigents, have been subject to discrimination “so unjustifiable as to be violative of due process.” Bolling v. Sharpe, 347 U. S. 497, 499.
Petitioners, citizens of Mexico allegedly brought into the United States illegally, belong to that class of persons who as material witnesses can be subpoenaed to testify. Each must suffer at least limited invasion of his personal liberty to fulfill his public obligation to provide evidence. See United States v. Bryan, 339 U. S. 323, 331; Blair v. United States, 250 U. S. 273, 281. Petitioners, however, also belong to a discrete subclass— those whose presence it might be impractical to secure by subpoena and thus were subject to detention pursuant *601to former Fed. Rule Crim. Proc. 46 (b) 1 if they could not post bail. The deprivation they suffer is longer and more extensive than that of the witness merely subject to a subpoena. They may spend months in jail awaiting the few minutes or hours they will spend testifying. Unlike other witnesses, they are not free to come or go while the trial is not actually in progress. Nevertheless, the justification for infringing their liberty remains the same. Former Rule 46 (b) was conceived as a tool2 to insure *602that the witness is available to testify, and any time spent incarcerated is spent as a direct result of the obligation that burdens all material witnesses. The comparison we are concerned with, then, is between the compensation paid to the incarcerated witness during the entire period his freedom to come or go is curtailed and the compensation paid to a nonincarcerated witness during the entire period he is subject to restraint. Although it is true, as the majority notes, that the nonincarcerated witness is paid nothing at all while court is not in session, the two classes are hardly comparably situated at the time, for the nonincarcerated witness is not subject to any substantial restraint as a result of his subpoena.
Congress has seen fit to compensate all material witnesses at the per diem rate of $20 for each day’s attendance “in any court” (as defined by the majority) and for the necessary travel time. 28 U. S. C. § 1821. Yet, Congress compensates those incarcerated pursuant to former Rule 46 (b) at the per diem rate of only $1. Thus, not only are petitioners subject to more extensive deprivation of personal freedom, they also are denied equivalent compensation while waiting to testify.3 Because former *603Rule 46 (b) provided that only witnesses who failed to post bail might be incarcerated, this discrimination in practice affected just the indigent and resulted, therefore, in a suspect classification based upon wealth. This invidious discrimination against the poverty-stricken cannot be supported by some speculative rational justification. Ortwein v. Schwab, post, p. 661 (Douglas, J., dissenting) ; United States v. Kras, 409 U. S. 434, 457 (opinion of Douglas and Brennan, JJ.); Boddie v. Connecticut, 401 U. S. 371, 383 (Douglas, J., concurring in result). Surely, the Government's desire to avoid the costs of compensation in addition to the increased costs of food, lodging, and security does not rise above that level.4 See Boddie v. Connecticut, supra, at 382; Shapiro v. Thompson, 394 U. S. 618, 633.
The majority “cannot say that there is no reasonable basis for distinguishing the compensation paid for pretrial detention from the fees paid for attendance at trial.” I am not certain I can agree even with that position. The magic transition period under the statute. 5 *604as construed by the majority is the beginning of trial. I find the distinction wholly arbitrary. I do not see how it bears any relevance to the quality of confinement; petitioners sacrifice their time waiting to testify whether or not court is in session.
Griffin v. Illinois, 351 U. S. 12, held that an indigent defendant is denied equal protection of the laws if he is barred from appealing on equal terms with other defendants solely because of his indigence. In Bandy v. United States, 82 S. Ct. 11, 7 L. Ed. 2d 9 (Douglas, J., in chambers), I concluded that “no man should be denied release [pending trial or judicial review] because of indigence.” Id., at 13, 7 L. Ed. 2d, at 11. This principle seems ever clearer and more forceful to me in circumstances where the imprisoned have not been charged with or convicted of a crime. We cannot allow the Government's insistent reference to these Mexican citizens as “deportable aliens” to obscure the fact that they come before us as innocent persons who have not been charged with a crime or incarcerated in anticipation of a criminal prosecution. It is true, of course, that petitioners do not challenge the constitutionality of confining a material witness. But, in their prayer for relief, they seek to enjoin the Government “from any further incarceration of any person under such rule under the present interpretation of 28 U. S. C. § 1821 at one dollar ($1.00) per day total payment.” I conclude that petitioners are entitled to this relief unless they are released on their personal recognizance.
Rule 46 (b), at the time this case arose and before Rule 46 was amended to conform it to the Bail Reform Act of 1966, read:
“Bail for Witness.
“If it appears by affidavit that the testimony of a person is material in any criminal proceeding and if it is shown that it may become impracticable to secure his presence by subpoena, the court or commissioner may require him to give bail for his appearance as a witness, in an amount fixed by the court or commissioner. If the person fails to give bail the court or commissioner may commit him to the custody of the marshal pending final disposition of the proceeding in which the testimony is needed, may order his release if he has been detained for an unreasonable length of time and may modify at any time the requirement as to bail.”
Mr. Justice Black and Mr. Justice Frankfurter dissented from submission of the original Rules of Criminal Procedure. 323 U. S. 821.
Mr. Justice Black and I in 1966 opposed the submission of certain amendments to the Rules of Criminal Procedure to the Congress. Mr. Justice Black's statement is to be found at 383 U. S. 1032, mine at 383 U. S. 1089. We thought at the time that some of the amendments presented serious constitutional questions.
The fact that the Court approved the Rules without reading them or debating them or weighing their merits does not, of course, preclude a challenge to their constitutionality in a given case.
But the imprimatur of this Court is on the Rules, and that gives them mighty weight. It is possible to read former Rule 46 (b) as permitting release on personal recognizance. But experience has shown that judges have not so read it. The result, as I indicate in this opinion, is that former Rule 46 (b) has borne down heavily on indigents who would be good risks but could not put up the money to buy a bail bond. Former Rule 46 (b) as so construed — and as *602applied in the present case — is therefore plainly unconstitutional. Filling of the jails of San Antonio with men whose only crime is the desire to find work and holding them there at the caprice of the prosecutor is shocking, to say the very least — and traceable to the easy, offhand way in which the Court has seemingly approved many Rules which touch not only matters of public security but individual liberties as well.
The Solicitor General asserts that “it is certainly not unreasonable or irrational for Congress to authorize a minimal sum as payment to deportable aliens. There is no indication that illegal aliens, like petitioners, even if employed, would have earned wages averaging $20 or $21 per day for a period of 30 or 60 days or longer.” This prompts two comments. In explaining a predecessor of the current statute, the Senate Report stated:
“The amounts arrived at in this bill are considered to be more fair than presently existing amounts, although it is recognized that *603certain witnesses will not, under the proposed rates, be adequately compensated. In order to fairly compensate everyone appearing as a witness it would be necessary to have either a graduated scale of fees, or, leave the amount of such fees in the discretion of the judge. Neither was considered feasible, and therefore the amounts arrived at herein are more or less arbitrary, but considered to be reasonably fair to the average witness.” S. Rep. No. 187, 81st Cong., 1st Sess., 2.
Also, if the statute is to be measured as it applies to aliens, it surely creates a suspect classification. See Takahashi v. Fish & Game Comm’n, 334 U. S. 410.
For each day the Government compensates a witness at the per diem rate of $20, it also pays the witness $16 to cover subsistence expenses. I cannot believe that it costs the Government more than $16 a day to feed an incarcerated witness. In any event, the witness should not be taxed when he is imprisoned for the convenience of the Government.
The majority tracks the legislative history of § 1821 and concludes that it is “unenlightening.” When compensation was first *604paid to incarcerated witnesses in 1853, Act of Feb. 26, 1853, § 3, 10 Stat. 167, they were paid $1 per day, or 50$ less than a witness merely attending court. No subsistence was paid, and we can assume that the differential related to this factor. Over the years, Congress has increased the compensation paid to material witnesses and added subsistence payments without increasing the compensation paid to incarcerated witnesses. Congress has not advanced any justification.