MEMORANDUM AND ORDER
PER CURIAM.Following a panel decision in this case, Igartua-De La Rosa v. United States, 386 F.3d 313 (1st Cir.2004), a petition for rehearing was filed seeking panel rehearing or rehearing en banc. The panel thereafter granted rehearing and asked the parties to address two issues: first, the plaintiffs’ claim that the United States was in default of its treaty obligations and, second, the availability of declaratory judgment concerning the government’s compliance with any such obligations. The rehearing order vacated the original panel decision. Igartua-De La Rosa v. United States, 404 F.3d 1, 2005 WL 857110 (1st Cir. Mar.14, 2005).
Given the importance of the issues, a majority of the active judges then voted that the rehearing should be en banc. The original panel comprised two active judges and one senior judge, all of whom participated in the panel decision which is now being reconsidered. Under the governing statute, a court that rehears a case en banc is comprised of all active judges, except that any senior judge of the circuit may participate in an en banc court “reviewing a decision of a panel of which such judge was a member.” 28 U.S.C. § 46(c) (2000).
The question has been raised whether the senior circuit judge who participated in the panel decision is eligible to sit on the en banc court in this case. A vote and a formal order have been requested on this issue. Accordingly, the active judges have determined, by a five to one vote, that the senior circuit judge is entitled to sit on the rehearing en banc.
For some years, it has been the practice of this court, when granting rehearing en banc, to vacate the panel decision in the same order. See e.g, United States v. Councilman, 385 F.3d 793, 793 (1st Cir.2004); Savard v. Rhode Island, 338 F.3d 23, 25 (1st Cir.2003) (en banc); Irons v. F.B.I., 880 F.2d 1446, 1447 (1st Cir.1989) (en banc). A reason for this practice is that a grant of rehearing en banc almost invariably results in a new decision, whether the outcome differs from or duplicates the result reached by the panel. No such order was issued in this case by the en banc court because the panel decision had already been withdrawn when panel rehearing was granted.
Given this past practice, it could be argued in most cases where this court has previously reheard cases en banc, that — in a mechanical sense — the en banc court is *32“reviewing” not the panel decision but the judgment of the district court. But this reading would ignore the thrust and purpose of the statute, the substance of what is happening when rehearing en banc is granted, and long established practice in this court. Each point deserves brief elaboration.
First, the thrust and purpose of the statute is to assure that where the senior circuit judge has participated in the panel decision, a rehearing of the case en banc will include the senior circuit judge as a member of the en banc court if he chooses to participate. See S.Rep. No. 97-275, at 27 (1981). This gives the en banc court the benefit of the knowledge and judgment of all of the judges of this circuit who sat on the panel that rendered the initial decision. That rationale directly supports the participation of the senior circuit judge in the en banc proceeding in this case.
Second, an en banc decision, following a panel decision, is in substance reviewing the work of the panel regardless of whether the panel opinion has or has not been formally withdrawn at the time of the rehearing. See, e.g., JOM, Inc. v. Adell Plastics, Inc., 193 F.3d 47, 49 (1st Cir.1999) (en banc) (reinstating portion of vacated panel opinion). The issue on rehearing en banc virtually always turns on something the panel decided or failed to decide. Whether the panel decision is withdrawn at the beginning or end of the en banc process, the en banc court’s action is in its essence one that either reaffirms or alters what the panel has decided.
Third, the unvarying practice of this court for many years has been to include on the en banc panel any senior circuit judge of this circuit who sat on the original panel and chooses to participate. This practice is not affected by the fact that the panel in this case withdrew its decision while the en banc petition was pending; given our past practice, a withdrawal of the panel decision by the en bane court itself has never prevented a senior circuit judge who sat on the panel from sitting on the en banc court.
Fourth, what little precedent exists on the interpretation of the statute directly supports the participation of the senior circuit judge in this case. The leading opinion, United States v. Hudspeth, 42 F.3d 1013 (7th Cir.1994) (Posner, C.J.), articulates the rationale set forth above; pertinently, that case upheld the inclusion on the en banc court of a senior circuit judge who had participated on the panel, even though the panel had not issued a decision prior to the grant of an en banc hearing. That rationale applies a fortiori to our own case in which the panel did issue a decision.
Accordingly, the senior circuit judge who participated in the panel decision in this case is entitled to sit on the en banc court.
It is so ordered.