224 F.3d 649 (7th Cir. 2000)
JAMES L. WEBB, Petitioner-Appellant,v.RON ANDERSON, Superintendent,  Indiana State Prison, Respondent-Appellee.
No. 97-3264
In the  United States Court of Appeals  For the Seventh Circuit
Argued September 14, 1999*Decided August 16, 2000

Appeal from the United States District Court  for the Northern District of Indiana, South Bend Division.  No. 97 C 337--Allen Sharp, Judge.
Howard B. Eisenberg (argued), Milwaukee, WI, for Petitioner-Appellant.
Michael A. Hurst, Jon B. Laramore (argued), Office of the Attorney General, Indianapolis, IN, for Respondent-Appellee.
Before BAUER, ROVNER and EVANS, Circuit Judges.
ILANA DIAMOND ROVNER, Circuit Judge.


1
James L. Webb, an inmate  of the Indiana State Prison, lost 90 days of good  time credit when prison authorities determined  that he had used marijuana based on a positive  urinalysis. After exhausting his administrative  remedies, Webb filed a petition for a writ of  habeas corpus, arguing that because prison  officials failed to maintain an adequate chain of  custody for the urine specimen, their  disciplinary decision lacks "some evidence" to  support it. See Superintendent, Mass.  Correctional Inst., Walpole v. Hill, 472 U.S.  445, 105 S. Ct. 2768 (1985). We conclude that the  omissions in the chain of custody form and  toxicology report at issue in this case are not  so serious as to preclude the prison's reliance  on them; together, the two documents constitute  "some evidence" that Webb used marijuana, and  that is all that the Due Process Clause of the  Fourteenth Amendment, as construed by the Supreme  Court, requires.

I.

2
The Indiana State Prison randomly tests its  inmates for drug and alcohol use. At 4:30 a.m. on  March 9, 1996, the prison facility at Michigan  City collected a urine sample from Webb. The  chain of custody slip confirms that the sample  was sealed in Webb's presence it bears his  initials as well as the name of the collecting  officer. R.6 Ex. A3; see also id. Ex. A2. The  parties agree that two subsequent entries on the  custody slip reflect that the specimen arrived at  the laboratory of a local hospital on March 12,  still with the seal intact. A March 15 toxicology  report, bearing Webb's name and prisoner number  and the same toxicology number as the chain of  custody form, indicates that the specimen was  analyzed on March 13 and tested positive for  cannabinoids, the active narcotic agent in  marijuana. R.6 Ex. A3. Neither the toxicology  report nor the chain of custody form, however,  identifies the technician who tested the  specimen, nor does either document confirm that  the specimen remained sealed until it was tested.  The prison received the test results on March 25.  R.6 Ex. A2.


3
Based on the lab report, the prison charged  Webb with the unauthorized use of a narcotic  drug. R.6 Ex. A4. Webb contested the charge,  asserting that "[t]here is no certified chain of  custody, and there is no name as to who did the  test." R.6 Ex. A5. A hearing took place on April  1, 1996. There, with the assistance of a lay  advocate, Webb reiterated his challenge to the  sufficiency of the evidence. The hearing officer  nonetheless found him guilty of the charge,  "[b]ased on the test results," and recommended  that the prison deprive him of 90 days' credit  for good time. R.6 Ex. A5. A reviewing officer  found no reason to disturb either the finding  that Webb had used marijuana or the recommended  sanction. That officer explicitly rejected Webb's  assertion that the chain of custody had been  broken, reasoning that the handling of his  specimen was adequately documented on the  toxicology form. R.6 Ex. A7. A final review by a  disciplinary review manager likewise rejected  Webb's argument. R.6 Ex. A9. Indiana does not  provide for state-court review of prison  disciplinary decisions, Hasty v. Broglin, 531  N.E.2d 200 (Ind. 1988), so at this point Webb had  exhausted his state remedies.


4
Webb filed a habeas petition alleging that the  prison had violated his right to due process. The  district court denied Webb relief, concluding  that the evidence underlying the disciplinary  decision satisfied the standard articulated in  Hill, 472 U.S. at 454, 105 S. Ct. at 2773. R.9,  Webb v. Parke, No. 97 C. 337, Order at 2 (N.D.  Ind. Aug. 7, 1997).1

II.
A.

5
When a state prisoner faces the loss of good  time credits for alleged misconduct, he is  entitled "to those minimum procedures appropriate  under the circumstances and required by the Due  Process Clause [of the Fourteenth Amendment] to  insure that the state-created right is not  arbitrarily abrogated." Wolff v. McDonnell, 418  U.S. 539, 557, 94 S. Ct. 2963, 2975 (1974). Among  other things, the "minimum requirements of  procedural due process" (id. at 558, 94 S. Ct. at  2976) demand that the findings of a prison  disciplinary board have the support of "some  evidence in the record." Hill, 472 U.S. at 454,  105 S. Ct. at 2773. This is a lenient standard,  see Lenea v. Lane, 882 F.2d 1171, 1175 (7th Cir.  1989), requiring no more than "a modicum of  evidence." Hill, 472 U.S. at 455, 105 S. Ct. at  2774. Even "meager" proof will suffice, so long  as "the record is not so devoid of evidence that  the findings of the disciplinary board were  without support or otherwise arbitrary." Id. at  457, 105 S. Ct. at 2775; see also Lenea, 882 F.2d  at 1175 ("Although 'some evidence' is not much,  . . . it still must point to the accused's  guilt."). It is not our province to assess the  comparative weight of the evidence underlying the  disciplinary board's decision. Hill, 472 U.S. at  455, 105 S. Ct. at 2774; see also Meeks v.  McBride, 81 F.3d 717, 720 (7th Cir. 1996), citing  Viens v. Daniels, 871 F.2d 1328, 1335 (7th Cir.  1989). "[T]he relevant question is whether there  is any evidence in the record that could support  the conclusion reached by the disciplinary  board." Hill, 472 U.S. at 455-56, 105 S. Ct. at  2774 (emphasis ours).


6
The toxicology report and the chain of custody  slip constitute "some evidence" supporting the  decision to impose disciplinary sanctions upon  Webb. The parties agree that the chain of custody  slip confirms the collection of the urine sample  from Webb and sealing of that specimen, the  transmission of the specimen to the hospital  laboratory, and the receipt of the sample by the  hospital in sealed condition. The toxicology  report, which bears Webb's name and prisoner  number and the same toxicology number as the  chain of custody form,2 in turn reveals that  the sample was analyzed within roughly twenty-  four hours after it arrived at the hospital and  that Webb's urine tested positive for  cannabinoids. Together, these documents establish  that Webb's sample was delivered to the hospital  in sealed condition, that the hospital laboratory  tested the sample, and that the analysis revealed  Webb's use of marijuana.


7
We regard the two omissions in the documentary  trail as significant, but not so material as to  preclude prison officials from relying on the  documents as evidence of Webb's marijuana usage.  Notwithstanding the omission of the name of the  technician who tested Webb's specimen, there is  no reason to doubt that the laboratory actually  analyzed the sample the toxicology report lays  out the various substances for which Webb's urine  was screened and the results for each. Similarly,  although the chain of custody form does not  confirm that Webb's specimen reached the  technician in a sealed condition, the record  gives us no reason to suspect that the specimen  may have been opened and tampered with during the  twenty-four hour period between its arrival at  the hospital on March 12 (at which point we know  that it was still sealed) and its testing on  March 13. The gap in the chain of custody form  and the anonymity of the technician who analyzed  Webb's sample certainly leave room for the  possibility that the sample was mishandled in  some way; conversely, filling in those omissions  would render that possibility more unlikely and  enhance the reliability of the test results. Yet


8
The Federal Constitution does not require  evidence that logically precludes any conclusion  but the one reached by the disciplinary board.  Instead, due process in this context requires  only that there be some evidence to support the  findings made in the disciplinary hearing.


9
Hill, 472 U.S. at 457, 105 S. Ct. at 2775; see  also Mackey v. Montrym, 443 U.S. 1, 13, 99 S. Ct.  2612, 2618 (1979); Higgs v. Bland, 888 F.2d 443,  449 (6th Cir. 1989). Absent some affirmative  indication that a mistake may have been made,  e.g. Meeks, 81 F.3d at 721 (prisoner number on  toxicology report did not match petitioner's  number, another prisoner had same name as  petitioner, and the two prisoners had been  confused before), we cannot say that the  toxicology report and chain of custody form fail  to qualify as "some evidence" from which prison  officials could conclude that Webb had used  marijuana. See United States v. Brown, 136 F.3d  1176, 1182 (7th Cir. 1998) (hypothetical  possibility of tampering does not render evidence  inadmissible, but goes instead to the weight of  the evidence).3

B.

10
28 U.S.C.  1915(a) bestows on courts the discretion to allow in indigent litigant to commence a suit or an appeal without pre-payment of the filing fee.  However, section 1915(b)(1) - a provision added by the Prison Litigation Reform Act of 1996 ("PLRA")- now provides that "if a prisoner brings a civil action or files an appeal in forma pauperis, the prisoner shall be required to pay the full amount of a filing fee." This court's opinions in Newlin v. Helman, 123 F.3d 429, 437-438 (7th Cir.1997), cert. denied, 522 U.S. 1054, 118 S.CT. 707, 139 L.Ed.2d 649 (1998), and Thurman v. Gramley 97 F.3d 185,1987 (7th Cir.1996), held that collateral proceedings like Webb's, which do not implicate the validity of a prisoner's underlying criminal sentence, constitute civil actions for the purposes of this provision.  In compliance with those decisions, as well as the terms of section 1915(b)(1) and (2) (which permit the fees to be paid over time), the district court ordered Webb to make an initial payment of $8.58 in order to have this appeal filed, and to remit monthly installment payments thereafter until he succeeded in paying the full appellate filing fee of $105 (which he eventually did).  See R. 18. Webb now asks that the filing fee be refunded, arguing (with the support of precedent from other circuits) that Newlin and Thurman were wrongly decided to the extent they characterized habeas actions like his own as "civil actions" for purposes of the PLRA.  We recently reached that very conclusion in Walker v. O'Brien, 216 F.3d 626, 633-37 (7th Cir.2000), in which we held that the PLRA does not apply to a petition for a writ of habeas corpus properly filed under either 28 U.S.C.  2241 or  2254.


11
Our holding in Walker does not entitle Webb to a refund of the appellate filing fee, however. As we noted in Walker itself "[a] court has within its discretion to insist that litigants proceeding IFP in non-PLRA cases must nonetheless pay a fee commensurate with their ability to do so." 216 F.3d at 638 n. 5, citing Longbehn v. United States, 169 F.3d 1082, 1083-84(7th Cir.1999). The fact that Webb managed, over time, to pay the filing fee in its entirety demonstrates that the full fee was within his means.  See Walker, 216 F.3d at 638 n. 5.

III.

12
Because the decision of prison officials to  revoke 90 days of good time credit has the  support of some evidence, we AFFIRM the judgment of  the district court denying Webb's petition for a  writ of habeas corpus. As this case does not  constitute a "civil action" for purposes of 28  U.S.C. sec. 1915(b), Webb was not required to pay  a fee in order to file the appeal. The Clerk of  the United States District Court shall therefore  refund the docketing fee that Webb paid in order  to proceed with his appeal. We thank Dean Howard  B. Eisenberg, whom we appointed to brief and  argue this case on Webb's behalf, for his  excellent service in this appeal, and we commend  both parties for their helpful briefs.



NOTES:


*
 We initially decided this case in Webb's favor  without argument pursuant to Federal Rule of  Appellate Procedure 34(a) and Circuit Rule 34(f)  and remanded the case to the district court for  an evidentiary hearing. See Webb v. Anderson, No.  97-3264, 172 F.3d 54, 1998 WL 870354 (7th Cir.  Dec. 11) (unpublished) (text in Westlaw). We  subsequently granted the State's petition for  rehearing, vacated our previous order, appointed  counsel for Webb, and set the case for argument.


1
 The district court suggested that the loss of  credits for good time served "probably does not  implicate a liberty interest under Sandin v.  Conner, 515 U.S. 472 [115 S. Ct. 2293] (1995).  R.9, Webb v. Parke, No. 97 C 337, Order at 1.  Here there is no dispute, however, that Indiana  law gives rise to a liberty interest in good time  credits. See Wolff v. McDonnell, 418 U.S. 539,  557, 94 S. Ct. 2963, 2975 (1974); Meeks v.  McBride, 81 F.3d 717, 719 (7th Cir. 1996).  Moreover, we have repeatedly concluded that the  loss of good time credits will support a claim  for the deprivation of due process. See Thomas v.  McCaughtry, 201 F.3d 995, 999 n.4 (7th Cir. 2000);  Sweeney v. Parke, 113 F.3d 716, 718 (7th Cir.  1997); Meeks, 81 F.3d at 719.


2
 Webb suggests that one digit in the sample's  eleven-character toxicology number may not match  the number reflected on the toxicology report  (Reply Br. at 3), but we disagree. What he (or  his counsel) reads as a "6" we believe to be a  "5," which conforms to the toxicology report. See  R.6 Ex. A3.


3
 We note that in Thompson v. Owens, 889 F.2d 500,  502 (3d Cir. 1989), the Third Circuit held that  a positive toxicology report alone sufficed as  "some evidence" of a prisoner's drug use without  any additional evidence as to the chain of  custody. We need not, and do not, go that far  here in sustaining the discipline imposed on  Webb. Cf. Bourgeois v. Murphy, 809 P.2d 472, 482  (Idaho 1991) ("when there is no documentation of  the chain of custody to show that that which was  analyzed by the laboratory came from the inmate  in question, there is no test from a legal  standpoint"); Sherer v. State, 668 So.2d 174, 174  (Ala. Crim. App. 1995); Byerly v. Ashley, 825  S.W.2d 286, 288 (Ky. App. 1991), cert. denied,  506 U.S. 934, 113 S. Ct. 364 (1992); see also  Cato v. Rushen, 824 F.2d 703, 705 (9th Cir. 1987)  ("there must be some indicia of reliability of  the information that forms the basis for prison  disciplinary actions"), citing, inter alia,  Mendoza v. Miller, 779 F.2d 1287, 1295 (7th Cir.  1985), cert. denied, 476 U.S. 1142, 106 S. Ct.  2251 (1986); accord, Viens, supra, 871 F.2d at  1335.


