Opinion for the court filed by Circuit Judge BUCKLEY.
Dissenting opinion filed by Circuit Judge WILLIAMS.
BUCKLEY, Circuit Judge:This is a petition for review of a decision of the Federal Labor Relations Authority holding that an employer could reduce remittances to a union of dues withheld from employees in order to compensate for over-payments previously made by the employer to the union. We reverse.
I. Background
Pursuant to 5 U.S.C. § 7115(a), management officials at Kelly Air Force Base in San Antonio, Texas deducted union dues from salaries of employees who had executed assignments authorizing the deductions. The deducted amounts were then remitted in a single check to the union (American Federation of Government Employees (“AFGE”) Local 1617, an affiliate of AFGE Council 214). The parties agree that the statute does not permit such deductions with respect to supervisory employees. See 5 U.S.C. §§ 7103(a)(2), 7112(b), 7115(b). In some instances, however, management continued to deduct union dues from employees for a short time following their promotion to supervisory positions. When the error was discovered, management reimbursed these employees, and deducted the amounts from the remittance to the union of dues withheld from other employees in a subsequent period.
The union challenged the deductions as an unfair labor practice in a proceeding before the Federal Labor Relations Authority (“FLRA” or “Authority”). The union relied on the rulings of two courts of appeals that the employer lacked statutory authority to reduce remittances to compensate for similar errors. American Fed’n of Gov’t Employees, Local 2612 v. FLRA, 739 F.2d 87 (2d Cir.1984) (“Griffiss ”); American Fed’n of Gov’t Employees, Local 1816 v. FLRA, 715 F.2d 224 (5th Cir.1983) (“Goodfellow ”). Nevertheless, both the administrative law judge who initially heard the case and the FLRA held that management had acted properly. The FLRA did not attempt to distinguish the previous cases but disagreed with their reasoning and declined to follow them.
II. Discussion
A. Statutory Issue
1. Standard of Review
We review the FLRA’s decision under the abuse of discretion standard. 5 U.S.C. *1460§ 7123(c); 5 U.S.C. § 706. The FLRA “is entitled to considerable deference when it exercises its ‘special function of applying the general provisions of the Act to the complexities’ of federal labor relations.” Bureau of Alcohol, Tobacco & Firearms v. FLRA, 464 U.S. 89, 97, 104 S.Ct. 439, 444, 78 L.Ed.2d 195 (1983) (“BATF”) (quoting NLRB v. Erie Resistor Corp., 373 U.S. 221, 236, 83 S.Ct. 1139, 1149, 10 L.Ed.2d 308 (1963)). We may not defer, however, to an administrative decision that is inconsistent with the plain language of a statute. BATF, 464 U.S. at 97, 104 S.Ct. at 444 (quoting NLRB v. Brown, 380 U.S. 278, 291-92, 85 S.Ct. 980, 988-89, 13 L.Ed.2d 839 (1965)); see also 464 U.S. at 98 n. 8, 104 S.Ct. at 444 n. 8. “If the statute is clear and unambiguous ‘that is the end of the matterQ] for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress.’ ” Board of Governors of the Fed. Reserve Sys. v. Dimension Fin. Corp., 474 U.S. 361, 368, 106 S.Ct. 681, 686, 88 L.Ed.2d 691 (1986) (quoting Chevron U.S.A., Inc. v. NRDC, 467 U.S. 837, 842-43, 104 S.Ct. 2778, 2781-82, 81 L.Ed.2d 694 (1984)); see also 474 U.S. at 373-75, 106 S.Ct. at 688-89.
2. Statutory Language
5 U.S.C. § 7115(a) provides:
If an agency has received from an employee in an appropriate unit a written assignment which authorizes the agency to deduct from the pay of the employee amounts for the payment of regular and periodic dues of the exclusive representative of the unit, the agency shall honor the assignment and make an appropriate allotment pursuant to the assignment.
We interpret this section as imposing an absolute duty on the employer to turn over to the union all funds deducted.
The FLRA argues that the funds erroneously withheld and remitted to the union constitute monies that the union wrongfully obtained, and which the union was obliged to repay. The Authority characterizes the deducted dues as union property, against which the employer can set off the union’s debt.
Even if we were to agree with the FLRA that a set-off is appropriate in this situation, we do not agree that the withheld dues are union property until they are actually delivered to the union. Cf. Goodfellow, 715 F.2d at 228 (withheld dues property of employees until delivered to union). The statute clearly was designed for the primary benefit and convenience of the employee. The employee has the right to decide whether to opt for withholding and to control the disposition of the funds so withheld. The employer acts as the agent of the employee with respect to the withheld funds. In the words of the statute, the employer “shall honor the assignment.” 5 U.S.C. § 7115(a). We agree with the Second Circuit that “shall honor” indicates “a mandatory intent”; the employer’s obligation to honor the dues check-off is “non-discretionary.” Griffiss, 739 F.2d at 89.
We are aided in this conclusion by the inclusion of the word “allotment” in 5 U.S.C. § 7115(a). To allot is to “set apart specific property ... to a distinct party.” Black’s Law Dictionary 70 (5th ed. 1979). An allotment therefore is an apportionment of an identifiable res to the person entitled to the property by law or contract. Under section 7115, the employer is authorized only to allot, not to set off. The statute does not contemplate the creditor’s remedy utilized here.
We find a helpful analogy in 5 C.F.R. § 550.312(e), which provides: “Allotters shall agree that disputes regarding any authorized allotment shall be a matter between the allotter [employee] and the allot-tee [union].” The employer is viewed as a neutral and passive intermediary between the employee and the union. Although this regulation appears to apply primarily to disputes between the employee and the union concerning the amount of dues owed, it also indicates that the employer is properly viewed as performing the passive and ministerial function of turning over employee's dues to the union. Cf. Griffiss, 739 F.2d at 89-90.
The FLRA relies on cases that hold, in different factual and legal contexts, that “assignments” operate as conveyances to *1461the assignee upon their execution. See, e.g., Seaboard Small Loan Corp. v. Ottinger, 50 F.2d 856, 857 (4th Cir.1931); Moutsopoulos v. American Mutual Ins. Co., 607 F.2d 1185, 1189 (7th Cir.1979). It therefore follows, says the Authority, that at the moment monies are withheld from the employee’s wages for payment of union dues, they become the union’s property. The FLRA points to private labor law cases that support this position. See, e.g., English v. Cunningham, 269 F.2d 517, 539 (D.C.Cir.) (employer who withholds dues under checkoff system is agent of union), cert. denied, 361 U.S. 897, 905, 80 S.Ct. 195, 4 L.Ed.2d 152, 181 (1959); Bassick Co. v. Bassick Local 229, 126 F.Supp. 777, 779 (D.Conn.1954); Kidde & Co. v. United Electrical, Radio & Machine Workers of America, 7 N.J. 528, 82 A.2d 184 (1951).
The FLRA overlooks a critical distinction between these private labor cases and the case at bar. When a union and an employer negotiate a dues check-off, as in the cases cited by the Authority, the courts rightly conclude that the employer acts primarily for the benefit of the union. As the dues check-off was obtained by the union, the withholding employer acts as the union’s agent. Indeed, the cases relied upon by the FLRA are premised specifically on the contractual relationship between the union and the employer. See, e.g., West Virginia Pulp & Paper Co. v. Lewis, 17 Misc.2d 94, 191 N.Y.S.2d 303, 307 (Sup.Ct.1958), aff'd mem., 8 A.D.2d 899, 187 N.Y.S. 2d 1002 (1959). Here, however, the withholding is authorized by statute and is made at the explicit request of the employee. The union has no role in negotiating the checkoffs, and the withholding employer acts solely as the employee’s agent.
We previously have cautioned against an inappropriate reliance on private labor precedents in litigation concerning the Federal Labor Relations Act (“Act”). As we recognized in Library of Congress v. FLRA, 699 F.2d 1280, 1287 (D.C.Cir.1983), labor-management relations in the public and private sectors are “determined by different statutory provisions and by different policy considerations.” Thus, private labor cases are relevant only when they involve statutory provisions and policy considerations comparable to those governing labor relations under the Act. See National Treasury Employees Union v. FLRA, 826 F.2d 114, 122 (D.C.Cir.1987). The dues withholding provision of the Act, 5 U.S.C. § 7115, has no counterpart in the National Labor Relations Act or the Labor Management Relations Act. In private cases, dues withholding is a matter reserved for collective bargaining. See United States Gypsum Co., 94 N.L.R.B. 112, 113 n. 7, amended, 97 N.L.R.B. 889 (1951), mod., 206 F.2d 410 (5th Cir.1953), cert. denied, 347 U.S. 912, 74 S.Ct. 475, 98 L.Ed. 1068 (1954); 2 The Developing Labor Law 1406 (Morris ed. 1983). We therefore find the FLRA’s reliance on private labor precedents misplaced.
The dissent relies on Lodge 2424, Int’l Ass’n of Machinists & Aerospace Workers v. United States, 564 F.2d 66, 215 Ct.Cl. 125 (1977), for the proposition that the government may recoup monies erroneously transmitted to the union by reducing the remittance in a later period. But in Lodge 2424, the government employer was specifically authorized by regulation to adjust remittances to the union in a subsequent period to correct for amounts erroneously withheld previously. 564 F.2d at 71. No similar authority obtains here. Lodge 2424 buttresses its conclusion by referring to cases such as United States v. Munsey Trust Co., 332 U.S. 234, 239-40, 67 S.Ct. 1599, 1601-02, 91 L.Ed. 2022 (1947), which indicate that the government can reduce its obligations under a contract through a set-off. Although these cases were relevant in Lodge 2424, which involved the interpretation of a collective bargaining agreement, they are not helpful in this case, which concerns a statutory, not a contractual relationship.
Finally, we are not persuaded by the Authority’s claim that the statutory requirement that the employer remit an “appropriate” amount permits the employer to reduce its allotment to the union. The statutory duty to remit an “appropriate” amount does not give the employer unfettered discretion to remit as much as it sees *1462fit. The employer must remit an “appropriate” amount, but the amount that is appropriate is the amount that the employer properly withheld from employees who executed valid check-offs.
The employer’s error in withholding and remitting dues from supervisory employees does not permit it to compound the error by reducing the allotment it is obliged to make. Even though the union receives the same sum as it was entitled to receive, the employees have suffered the conversion by the employer of wages they still own.
We do not decide whether the employer could recover the amounts improperly withheld from supervisory employees and remitted to the union in a separate action brought against the union. Cf Griffiss, 739 F.2d at 90 n. 1.
B. Rights Under Master Labor Agreement
Because we hold that the withheld funds are the property of the employees, we find it unnecessary to remand for a determination concerning the parties’ rights under the Master Labor Agreement. Section 8.08 of the Agreement provides:
Deductions will not be made for an employee who has been in a nonpay status for a pay period. Administrative errors in remittance checks and/or improper deductions will be corrected by the Employer and adjusted in the next remittance check to be issued to the Union local. If the Union local is not scheduled to receive a remittance check after discovery of the error, the Union agrees to promptly refund the amount of the erroneous remittance.
Even if this provision were construed as applying to the withholding error committed here, an issue on which we do not pass, the contract between the union and the employer cannot alter the property rights of the employees in their wages. These rights, as we have held, are not extinguished until the withheld dues are delivered to the union.
C. Collateral Estoppel
Petitioner asserts that the interpretation of the statute advanced by the FLRA was fully litigated and twice rejected by federal appellate courts. Petitioner claims that because the FLRA has had a full opportunity to convince two courts of its position, it is collaterally estopped to present these views to us.
United States v. Mendoza, 464 U.S. 154, 104 S.Ct. 568, 78 L.Ed.2d 379 (1984), held that the rules governing offensive issue preclusion between private litigants do not apply when the government is a party. Collateral estoppel will apply against the government only if mutuality of parties exists. United States v. Stauffer Chemical Co., 464 U.S. 165, 104 S.Ct. 575, 78 L.Ed.2d 388 (1984). In Stauffer, the EPA sought to inspect one of Stauffer’s plants in Wyoming using private contractors. The Tenth Circuit ultimately held that the EPA lacked authority to employ private parties in this fashion. Meanwhile, the EPA attempted to inspect another of Stauf-fer’s plants in Tennessee, again with private contractors. The Supreme Court held that the EPA was estopped to claim it was authorized to use private contractors to inspect the Tennessee plant. Because the parties were the same in both actions, Stauffer was permitted to invoke defensive collateral estoppel.
In this case, the previous adjudications of the statutory issue involved different locals of the same union. An adjudication against one local does not necessarily bind the parent union, and a fortiori does not bind other locals. See, e.g., Carbon Fuel Co. v. United Mine Workers of America, 444 U.S. 212, 100 S.Ct. 410, 62 L.Ed.2d 394 (1979) (parent union cannot be held liable for actions of local unless authorized).
Mutuality may obtain if the parent union controlled the previous litigation. One who controls litigation, even if not named as a party, may be subject to collateral estoppel. See Montana v. United States, 440 U.S. 147, 153-55, 99 S.Ct. 970, 973-75, 59 L.Ed.2d 210 (1979). Montana held that the U.S. was bound by a previous adjudication even though it had not been a *1463party: the government had required the previous lawsuit to be filed, reviewed and approved the complaint, financed the litigation, directed the appeal, and submitted an amicus brief. Id.
In American Postal Workers Union v. United States Postal Service, 736 F.2d 317, 318-19 (6th Cir.1984), a local of a national union sought to enjoin the Postal Service from disciplining workers for absences due to use of sick leave. The Postal Service sought dismissal, arguing that the union’s claim was res judicata. The Postal Service pointed to another case filed by another local of the same union. The court disagreed. The parties were not identical in the two suits, and there was no showing of privity between the two locals. The fact that both locals were under the auspices of a national union was insufficient in itself to establish privity, as the national union was not a party. The court implied, however, that res judicata would apply if the national had been as involved in both cases as a co-party would have been. 736 F.2d at 319.
Petitioner failed to present evidence in the administrative proceeding demonstrating that the parent union controlled both the previous and the instant litigation. The only evidence before us on this issue is the overlap of counsel in Griffiss, Goodfellow, and this case. But commonality of counsel, standing alone, is insufficient to establish mutuality. “We know of no basis for holding that the mere fact that the same attorney represented the parties in another action that has gone to judgment makes the latter res adjudicata against his client.” Ramey v. Rockefeller, 348 F.Supp. 780, 785 (E.D.N.Y.1972) (three-judge court); see also Garza v. Henderson, 779 F.2d 390, 393-94 (7th Cir.1985); Freeman v. Lester Coggins Trucking, Inc., 771 F.2d 860, 864 (5th Cir.1985). The inference of mutuality is particularly weak here, as there is no evidence that common counsel initiated each case.
As petitioner had the burden of proving res judicata, the absence of evidence in the record establishing mutuality requires us to reject the collateral estoppel claim.
III. Conclusion
The petition for review is granted, and the decision of the FLRA is reversed.
So ordered.