(concurring) :
Although I concur in the result reached in Judge Timbers’ carefully considered opinion, I am not entirely in agreement with one aspect of its reasoning.
I agree that the Board’s finding that the parties reached a prior understanding, partly oral and partly written, regarding temporary assignment procedures was supported by substantial evidence and that the Union’s unilateral embargo in disregard of that understanding violated its obligation “to bargain collectively” in accordance with § 8(b)(3), 29 U.S.C. § 158(b)(3). But in my view we could enforce the Board’s order, as interpreted by it, only if we agreed with it that the past practices' and prior understandings as to assignment of temporary supervisors were “contained in a contract” as that phrase is used in § 8(d), 29 U.S.C. § 158(d), which defines the phrase “to bargain collectively.” I would so hold. Under such a holding the Company would not be “required ... to agree to, or even to bargain with the Union about, changing the existing agreement during its term.” Decision of the Board, Appendix 6. The reasoning of the majority opinion, however, by relying on the *783“contract’s silence” and analogizing the case to Westgate, New York Dist. Council v. N. L. R. B., 453 F.2d 783, 787 (2d Cir. 1971), cert. denied, 405 U.S. 988, 92 S.Ct. 1251, 31 L.Ed.2d 455 (1972), upon which the Trial Examiner relied, should logically permit the Union at any- time during the term of the contract to initiate bargaining on the issue, since the contract is “silent on the matter.” The Board, modifying the Trial Examiner’s proposed order, rejected such reasoning.
Section 8(d) 1 bars reopening or modification of an existing collective bargaining agreement except upon stated conditions that were not followed by the Union in this case. It further provides that these conditions “shall not be construed as requiring either party to discuss or agree to any modification of the terms and conditions contained in a contract for a fixed period. . . . ” (emphasis supplied). I am persuaded that, absent a clause to the effect that the formal agreement incorporates all understandings between the parties — and no such term is found in the formal agreement here — a prior understanding of the type in this case, partly oral and partly written, may constitute a term of the “contract” between the parties within the meaning of § 8(d) even though it has not been physically incorporated in a formal collective bargaining agreement. This view is amply supported by precedent. United Steelworkers v. NLRB, 456 F.2d 248, 249 (3d Cir. 1972); Jacobs Manufacturing Co., 94 N.L.R.B. 1214, 1227 (1951) (concurring opinion), enfd., NLRB v. Jacobs Mfg. Co., 196 F.2d 680 (2d Cir. 1952); Spei-del Corp., 120 N.L.R.B. 733, 738 (1958).
“I believe that this Respondent was not under a duty to discuss the Union’s group insurance demand.
* * ■» -X- * *
“In my opinion, it is only reasonable to assume that rejection of the Union’s basic proposal, coupled in this particular instance with enhancement of the substantive benefits, constituted a part of the contemporaneous ‘bargain’ which the parties made when they negotiated the entire 1948 contract. In the face of this record as to what the parties discussed and did, I believe that it would be an abuse of this Board’s mandate to throw the weight of Government sanction behind the Union’s attempt to disturb, in midterm, a bargain sealed when the original agreement was reached.
“To hold otherwise would encourage a labor organization — or, in a Section 8(b)(3) case, an employer — to come back, time without number, during the term of a contract, to demand resumed discussion of issues which, although perhaps not always incorporated in the written agreement, the *784other party had every good reason to believe were put at rest for a definite period.” Jacobs Manufacturing Co., supra at 1227-28.
In Westgate, relied upon by the majority, the failure of the parties to reach agreement on production quotas barred the Union from unilaterally modifying the 35-hour work week provision of the ‘formal collective bargaining agreement and entitled the employer to restrict the Union to the four corners of that agreement.2 I do not view that case as supporting the proposition upon which our decision depends, namely, that where earlier understandings constitute part of the contract between the parties they may rely upon such terms, even though the terms are not found within the four corners of the formal written agreement.
. Section 158(d) defines the phrase “to bargain collectively” as the
“performance of the mutual obligation of the employer and the representative of the employees to meet at reasonable times and confer in good faith with respect to wages, hours, and other terms and conditions of employment . Provided, That where there is in effect a collective-bargaining contract covering employees in an industry affecting commerce, the duty to bargain collectively shall also mean that no party to such contract shall terminate or modify such contract, unless the party desiring such termination or modification—
(1) serves a written notice upon the other party to the contract of the proposed termination or modification sixty days prior to the expiration date.
(2) offers to meet and confer with the other party. . . .
(3) [notifies the appropriate conciliation services]. . .
(4) [does not resort to strike or lock out and gives full force to contract] for a period of sixty days after such notice is given or until the expiration date of such contract, whichever occurs later: “ . . . [t]he duties so imposed [2-4] shall not be construed as requiring either party to discuss or agree to any modification of the terms and conditions contained in a contract for .a fixed period, if such modification is to become effective before such terms and conditions can be reopened under the provisions of the contract. . . . ” 29 U.S.C. § 158(d). (Emphasis supplied)
. “In our opinion the Union’s enforcement of the 10-room rule violates the term of the September 9th collective bargaining agreement that stipulates that the standard work week for journeymen painters shall consist of five seven-hour days. ■ By enforcing the rule the Union is in substance modifying this term to stipulate the journeymen are not to work a five day, seven-hour per day work week, but are to work only so long as it takes them to paint 10 rooms. We therefore agree with the Board that before the Union can enforce this modification of the collective bargaining agreement, it must bargain collectively. . . . This obligation includes, of course, compliance with the four classes of section 8(d).” 453 F.2d 783, 787 (2d Cir. 1971).