delivered the opinion of the Court.
Pеtitioner Thomas West brought a “hybrid” suit against his employer, his union, and his union representative under the Railway Labor Act. He alleged that the employer had breached the collective-bargaining agreement and that the union and its representative had breached their duty of fair representation. The parties agree, for the purpose of our review of the Court of Appeals’ judgment, that petitioner’s cаuse of action accrued on March 25,1984, the date petitioner learned of the alleged breach of the union’s duty of fair representation. His complaint was filed on September 24, 1984, less than six months after the statute of limitations began to run. The summonses and complaints were mailed to respondents on October 10, 1984. Respondents acknowledged service of the complaint on dates ranging from October 12, 1984, thrоugh November 1, 1984. Thus, both the date on which the complaints were mailed and the date when the first acknowledgment of service was made were more than six months after the statute began to run.
Because service was not effected within the 6-month period prescribed in § 10(b) of the National Labor Relations Act,
1
Congress did not enact a federal statute of limitations that is expressly applicable to federаl duty of fair representation claims. In
DelCostello
v.
Teamsters,
The only gap in federal law that we intended to fill in
DelCostello
was the appropriate limitations period. We did not intend to replace any part of the Fеderal Rules of Civil Procedure with any part of § 10(b) of the National Labor Relations Act. Rule 3 of the Federal Rules of Civil Procedure provides that a civil action is commenced by filing a complaint with the cоurt, and Rule 4 governs the procedure for effecting service and the period within which service must be made. The clerk of the district court must “forthwith issue a
Inevitably our resolution of cases or controversiеs requires us to close interstices in federal law from time to time, but when it is necessary for us to borrow a statute of limitations for a federal cause of action, we borrow no more than neces
The judgment of the Court of Appeals is reversed, and the case is remanded fоr further proceedings consistent with this opinion.
It is so ordered.
Notes
Section 10(b) of the National Labor Relations Act, 49 Stat. 453, as amended, 29 U. S. C. § 160(b), provides:
Although
DelCostello
and the Sixth Circuit’s opinion in
Macon
v.
ITT Continental Baking Co.,
Under § 10(b), the еmployee’s charge is timely if a copy is served personally or mailed within the limitations period. See 29 CFR § 102.113(a) (1986). The complaint in an unfair labor practice proceeding is filed by the General Counsel after he or she has investigated the employee’s charge. See 29 U. S. C. § 153(d).
When the underlying cause of action is based on state law, and federal jurisdiction is based on diversity of citizenship, state law not only provides the appropriate period of limitations but also determines whether service must be effected within that period.
Walker
v.
Armco Steel Corp.,
Our holding that the statute of limitations was tolled when the complaint was filed eliminates the potential difficulty of determining the actual dates on which serviсe of the complaint was made on the various defendants.
In some cases, the determination of the length of the borrowed period may require examination of the tolling rules that are followed in the jurisdiсtion from which the statute of limitations is borrowed. See,
e. g., Wilson
v.
Garcia,
Respondents also argue that §10(b)’s service requirement must be adoptеd in order to assure that defendants receive prompt notice of suit against them. The requirement of timely service in Rule 4(j) satisfies this need without recourse to the service requirement of § 10(b). While it is possible that а defendant Will not be served with the complaint until 10 months after the cause of action accrues, this result is not inconsistent with our adoption of a 6-month statute of limitations for breach of contract/ breach of duty of fair representation claims. See
DelCostello
v.
Teamsters,
