Subsequent to our decision in Delta Air Lines, Inc. v. C. A. B., U.S.App.D.C.,
Generally, costs on appeal are taxed in accordance with Rule 39, Fed. R.App.P., as statutorily authorized by 28 U.S.C. § 1920 (1970). However, situations inevitably arise in which the rule is not specifically dispositive, such as the case
sub judice
2
Rule 39(a), set forth in the margin,
3
essentially implements the long established practice of taxing costs in favor of the prevailing party, and conversely, against the losing party.
See, e. g.,
Saunders v. Washington Metropolitan Area Transit Authority, 164 U.S.App.D.C. -,
*388 The essence of Delta’s opposition is that, to Delta’s knowledge, it has not been the practice of this court to tax costs either in favor of or against inter-venors in CAB review proceedings.
We turn first to the broader issue of whether costs should be taxed either for or against intervenors in any agency review proceedings. Because taxation of costs generally is a matter simply ordered by the Clerk of the Court in the absence of opposition by the parties, it is seldom the subject of published court opinions.
The court asked its Clerk to inquire of the other circuits, to determine their practices, if any, in this regard. It develops that, of those circuits confronting the problem, the prevailing practice has been to treat intervenors in agency actions like any other prevailing or losing party, as the case may be.
See, e. g.,
N.L.R.B. v. Oil, Chemical and Atomic Workers Int’l Union,
Finally, Delta directs our attention to two dockets in which this court reversed Board determinations, and thereafter entered orders taxing costs against the Board without any orders taxing costs against the intervenors on the Board’s side. 5 While there is a prevailing practice of taxation of costs for or against intervenors as prevailing or losing parties, it is a practice, not an ironclad rule. Not all cases are alike, and not all require like treatment. Rule 39 (a) explicitly recognizes our discretion, qualifying every phrase with “unless otherwise ordered” or similar language. The circumstances of a particular case may lead a court to depart from the prevailing practice. Beyond the obvious initial determination of whether the intervenor was on the winning or losing side, such other factors as the relative merit of the intervenor’s contribution, the novelty of the issues, the necessity of intervention and the public interest, to name a few, may also be relevant considerations in regard to taxation of costs. 6 The cases cited by Delta, while relevant, are not controlling.
In the instant case the intervenors were prevailing parties who substantially contributed to our resolution of the issues presented. We think they should be allowed their costs. 7 Motion denied.
Notes
. Delta informs us that all other petitioners in Delta Air Lines, Inc. v. C.A.B.,
. See also Rule 15, General Rules, U.S.App.D.C. (1968).
. Fed.R.App.P. 39(a) reads:
Except as otherwise provided by law, if an appeal is dismissed, costs shall be taxed against the appellant unless otherwise agreed by the parties or ordered by the court; if a judgment is affirmed, costs shall be taxed against the appellant unless otherwise ordered; if a judgment is reversed, costs shall be taxed against the appellee unless otherwise ordered; if a judgment is affirmed or reversed in part, or is vacated, costs shall be allowed only as ordered by the court.
. After Allied Indus. Workers, AFL-CIO Local Union No. 289 v. N.L.R.B.,
. The orders are unreported. The decision on the merits appear in Continental Air Lines, Inc. v. C.A.B.,
. For a discussion of certain of these factors as they may relate to taxation of costs,
see,
Rural Housing Alliance v. U. S. Department of Agriculture, Statement by Chief Judge Bazelon On Bill of Costs, 167 U.S.App.D.C. -,
. We agree with Delta that some of the in-tervenors’ requested costs are excessive, and shall make adjustments.
