OPINION OF THE COURT
ROSENN, Circuit Judge.This appeal raises an interesting question of entitlement to overtime compensation arising out of the interfacial tensions of two federal regulatory statutes, the Motor Carrier Act of 1935 (MCA), Act of August 9, 1935, c. 498, 49 Stat. 543 and the Fair Labor Standards Act (FLSA), 29 U.S.C. §§ 209, 216 (West Supp.1992). The plaintiffs are a group of field engineers previously employed by U.S. Computer Services, d/b/a CableData (CableData) seeking overtime compensation pursuant to the FLSA. The plaintiffs frequently traveled interstate as part of their job duties, carrying tools, component parts, and equipment in order to install, maintain, or repair customers’ computers. The district court held that the plaintiffs were exempt from the FLSA’s overtime compensation requirements pursuant to the FLSA’s Motor Carrier Act exemption. The plaintiffs appealed and we affirm.1
I.
The material facts are not in dispute. CableData is a privately-owned corporation headquartered in California. It provides computer hardware and software, installa*411tion, maintenance, and repair service of its computer equipment to its customers engaged in the cable television business. The plaintiffs were assigned to the company’s Northeast Region Office, located in Broo-mall, Pennsylvania. This office regularly services customers located in Pennsylvania, New York, New Jersey, Delaware, Maryland, Washington, D.C., Virginia, West Virginia, and other states as needed.
The primary duties of the plaintiffs were to provide technical expertise to CableDa-ta’s customers and to perform installation, preventive maintenance, diagnostics, and repairs on the customers’ computer hardware. The plaintiffs routinely traveled to customer sites, both in and out of Pennsylvania, in order to perform these services. If the customer sites were within four to six hours’ drive, the field engineers drove their personal vehicles and transported their tool kits, replacement parts, and equipment. For customer sites located at a greater distance, the field engineers traveled by air and drove rental automobiles from the airport.
The plaintiffs filed a complaint against CableData seeking overtime compensation allegedly due pursuant to the FLSA, the Pennsylvania Minimum Wage Act of 1968 (PMWA), 43 P.S. §§ 333.101-333.115 (West Supp.1992), and the Pennsylvania Wage Payment and Collection Law (WPCL), 43 P.S. §§ 260.1-260.11a (West Supp.1992). CableData filed a motion for summary judgment under the MCA, and the plaintiffs filed a cross-motion for summary judgment. The court granted summary judgment in favor of CableData with respect to the plaintiffs’ FLSA claims and subsequently certified the judgment pursuant to Federal Rule Civil Procedure 54(b).2
In granting summary judgment, the court concluded: (1) the plaintiffs were subject to the MCA exemption from the FLSA’s overtime compensation requirements; (2) the United States Department of Transportation (DOT) retained the authority to establish maximum hours of employment for the plaintiffs, notwithstanding the lightweight vehicle exemption promulgated by the DOT; and (3) the court was prohibited from reaching a contrary result in the absence of Congressional action limiting the DOT’S power to regulate motor private carriers by passenger automobile. The plaintiffs appealed and the Secretary of Labor filed an amicus curiae brief.3 We have jurisdiction to hear this interlocutory appeal pursuant to 28 U.S.C. § 1292(b).
II.
To obtain a summary judgment, the proponent of the motion has the initial burden of identifying evidence, from the sources enumerated in Federal Rule Civil Procedure 56(c), which demonstrates the absence of a genuine issue of material fact and which establishes the movant’s entitlement to judgment as a matter of law. Anderson v. Liberty Lobby, 477 U.S. 242, 247, 106 S.Ct. 2505, 2509, 91 L.Ed.2d 202 (1986). When confronted with a properly supported motion for summary judgment, the opposing party is required to produce, from the same sources enumerated in Rule 56, contrary evidence which would support its position. Id. at 250, 106 S.Ct. at 2511. In reviewing a grant of summary judgment, we must draw all possible inferences from the record in the light most favorable to the party opposing the motion. Bechtel v. Robinson, 886 F.2d 644, 647 (3d Cir.1989).
*412Congress enacted the MCA in 1935, to promote efficiency, economy, and safety in the rapidly burgeoning motor transportation industry. See United States v. American Trucking Ass’ns, Inc., 310 U.S. 534, 538-39, 60 S.Ct. 1059, 1061-62, 84 L.Ed. 1345 (1940). To advance these goals, the MCA gave the Interstate Commerce Commission (ICC) authority to establish requirements for recordkeeping, safety of operation, qualifications, and maximum hours of work for “common carriers” and “contract carriers” by motor vehicle. See 49 U.S.C. § 304(a)(1) & (2) (repealed). The Act also gave the ICC similar regulatory power over employees of “private carriers” by motor vehicle if the ICC found that such requirements were necessary to promote the safety of operation. See id. at § 304(a)(3) (repealed).
In 1938, Congress enacted the FLSA to protect covered workers from substandard wages and oppressive working hours. See Barrentine v. Arkansas-Best Freight Sys., Inc., 450 U.S. 728, 739, 101 S.Ct. 1437, 1444, 67 L.Ed.2d 641 (1981), cert. denied, 471 U.S. 1054, 105 S.Ct. 2116, 85 L.Ed.2d 480 (1985). The FLSA required employers to compensate such employees at a minimum of one and one-half times their standard hourly wages for time worked per week in excess of forty hours. See 29 U.S.C. § 207(a)(1). Congress ensured that regulatory jurisdiction under the MCA and the FLSA would not overlap by providing that the FLSA did not apply where the ICC already had power to set maximum hours. See Levinson, 330 U.S. at 661-62, 67 S.Ct. at 938. Specifically, the FLSA exempted from its overtime requirements “any employee with respect to whom the [ICC] has power to establish qualifications and maximum hours of service pursuant to the provisions of section 304 of Title 49.” See 29 U.S.C. § 213(b)(1). It is the employer’s burden to affirmatively prove that its employees come within the scope of the overtime exemption, and any exemption from the Act must be proven plainly and unmistakably. Martin v. Cooper Elec. Supply Co., 940 F.2d 896, 900 (3d Cir.1991) (citations omitted).
In 1966, Congress transferred the authority to regulate under section 304 of the MCA from the ICC to the DOT. See Act of Oct. 15, 1966, P.L. 89-670, § 6(e)(6)(C), 80 Stat. 939; 49 U.S.C. § 1655(e)(6)(C). In 1983, Congress repealed section 304 and recodified the section without substantive change as 49 U.S.C. § 3102. See Act of Jan. 12, 1983, P.L. 97-449, § 7(b), 96 Stat. 2444. Section 3102 gives the DOT authority to regulate "motor carriers”4 and “motor private carriers.”5 Motor private carriers are those that are neither common nor contract carriers, and that (1) transport property by motor vehicle in interstate commerce; (2) are the “owner, lessee, or bailee of the property being transported”; and (3) transport the property “for sale, lease, rent, or bailment, or to further a commercial enterprise.” See 49 U.S.C. § 10102(16).
Preliminarily, the plaintiffs present two statutory-based claims, contending that Ca-bleData does not fit within the plain language of the MCA exemption. First, they assert that the MCA exemption from the FLSA overtime requirements does not apply to motor private carriers because section 3102(a)(1) applies to transportation “described in sections 10521 and 10522 of this title” and these sections speak only of “motor carriers,” which are later defined to mean motor common carriers and motor contract carriers, 49 U.S.C. § 10102(13). *413However, section 3102(a)(1) simply refers to sections 10521 and 10522 for a description of the type of transportation subject to the DOT’s jurisdiction, that is, interstate transportation. See, e.g., Griffin v. Consolidated Foods Corp., 587 F.Supp. 921, 922 (W.D.N.C.1984), aff'd, 771 F.2d 826 (4th Cir.1985). The plaintiffs’ proffered interpretation would render section 3102(b)(2) meaningless.
Second, the plaintiffs argue that the DOT does no.t have the power to regulate them because they were engaged in a business other than transportation and the transportation in question was in furtherance of their primary business of servicing computer equipment. Under the “primary business test,” the ICC lacks jurisdiction over the transportation of property by motor vehicle by a person engaged in a non-transportation business when the transportation is within the scope of and furthers the primary business of such person. 49 U.S.C. § 10524(a).
Congress adopted section 10524(a) because of a proliferation of “buy-sell” agreements whereby carriers attempted to avoid ICC regulation. See Ryder Truck Lines, Inc. v. United States, 716 F.2d 1369, 1373 n. 4 (11th Cir.1983), cert. denied, 466 U.S. 927, 104 S.Ct. 1708, 80 L.Ed.2d 181 (1984). By purchasing the goods to be transported and then selling them upon reaching their destination, the carriers avoided ICC rate and licensing requirements as well as federal excise taxes. Id. Section 10524(a) has no application in this case. The section merely exempts motor private carriers from the licensing, permit, and certificate requirements imposed upon motor carriers by the ICC pursuant to 49 U.S.C. §§ 10921-10935; it does not serve to deprive the DOT of its power to regulate the qualifications and maximum hours of service of employees of motor private carriers pursuant to 49 U.S.C. § 3102(b)(2). See American Trucking Ass’ns, 672 F.2d at 851 (common and contract motor carriers are subject to ICC regulation but motor private carriers are exempt from such regulation). The MCA exemption thus applies independent of the ICC’s jurisdiction over a motor private carrier.
The record shows that the plaintiffs transported property by motor vehicle in interstate commerce, that CableData owned the property transported, and that the plaintiffs transported the property to further CableData’s commercial enterprise.6 Therefore, the plaintiffs literally fell within the MCA exemption to the FLSA. The plaintiffs argue, however, that the DOT has waived its regulatory power under the MCA exemption because it has not sought to regulate operations such as CableData’s.
In 1984, Congress enacted the Motor Carriers Safety Act (MCSA), 49 App. U.S.C. § 2501 et seq., which directed the DOT to issue various regulations to further safety in the operation of “commercial motor vehicles.” Commercial motor vehicles are those vehicles weighing over 10,000 pounds, designed to transport more than 15 passengers, or used in the transportation of hazardous materials. Id. at § 2503(1); 49 C.F.R. § 390.5. In response to the MCSA, the Federal Highway Administration (FHWA) amended the Federal Motor Carrier Safety Regulations (FMCSR), see 49 C.F.R. § 390.1-390.37 (Nov. 15, 1988).7 The DOT regulations do not apply to the *414plaintiffs because the motor vehicles driven by them in their duties for CableData weigh less than 10,000 pounds.
The district court concluded that the DOT’s failure to exercise its power to regulate does not mean that it has waived it. The court relied on Southland Gasoline Co. v. Bayley, 319 U.S. 44, 63 S.Ct. 917, 87 L.Ed. 1244 (1943). In that case, the plaintiffs, employees of a motor private carrier, argued that the ICC had no power to regulate their working hours prior to the time it issued regulations for private carriers. At that time, the ICC had authority to establish working hours for private carriers “if need therefor is found.” See 319 U.S. at 47, 63 S.Ct. at 919 (citing MCA § 204(a)(3); 49 U.S.C. § 304(a)(3) (repealed)). The employees asserted that because the ICC did not regulate or make a finding that regulation was necessary prior to 1940, they were entitled to overtime compensation under the FLSA up until the time the ICC found need to regulate. The Court rejected this argument and held that the requirement to make a finding of need before issuing regulations did not affect the existence of the ICC’s power to regulate. See 319 U.S. at 47-48, 63 S.Ct. at 919; accord Levinson, 330 U.S. at 661, 67 S.Ct. at 938.
Similar to the statute at issue in Southland, 49 U.S.C. section 3102(b)(2) allows the DOT to regulate working hours of private carriers only where “needed to promote safety of operation”. The district court reasoned that because section 3102 recodified section 304 without substantive change, Southland is controlling.8 Moreover, in 1984, Congress amended section 3102 to require that the DOT “consider the costs and benefits” of amending the section, but it did not limit the section to apply only to commercial motor vehicles. See 49 U.S.C. § 3102(d). The district court thus found that the DOT’s failure to find regulation necessary in a particular area does not mean that the DOT has waived its power to regulate pursuant to section 13(b)(1) of the FLSA.
In 1977, the DOT published an interpretation of the FMCSR:
The [FMCSR] were designed primarily to apply to medium and heavy-duty commercial vehicles, and in many instances the Regulations are not suitable for passenger cars. Various parts of the FMCSR contain exemptions for the operation and driving of passenger automobiles. The Bureau, therefore, has not required compliance with the Regulations by private carriers of property insofar as they engage in the transportation of property in an incidental manner in passenger cars.
42 Fed.Reg. 60,079-60,080 (1977); 40 Fed. Reg. 50,677 (1975). The plaintiffs and the amicus argue that this “passenger automobile exemption” supports the conclusion that the DOT exempted the operation of passenger vehicles from the application of the MCA. The DOT interpretation, however, merely reflects the DOT’s historic focus on safety regulations for medium and heavy-duty commercial vehicles without relinquishing its power over passenger vehicles engaged in transporting property in interstate commerce.
When issuing the FMCSR, the DOT recognized the “Congressional policy of applying available Federal motor carrier safety resources to larger vehicles.” See 53 Fed. Reg. 18,042, 18,044 (1988). The DOT stated that it “historically regulated all commercial motor vehicles engaged in interstate commerce,” but that it had “long focused its activities on larger vehicles” because vehicles weighing 10,000 pounds or less “have operating characteristics similar to a large automobile and generally pose no greater safety risk ... when used on the highway.” Id. at 18,054. Moreover, as observed by the district court, the DOT’s statement reflects its interpretation of the federal motor carrier regulations only and not of section 304 of the MCA. Nothing in *415the DOT’s statement suggests that it has determined that the MCA does not apply to transportation of property by passenger vehicles. Additionally, as discussed below, because the plaintiffs’ transportation of property in passenger cars is more than incidental, the “passenger automobile exemption” is inapplicable.
The plaintiffs further argue that the DOT’s failure to regulate operations like CableData leaves the inference that it does not believe it has the authority to do so. They assert that the DOT’s exclusion of lightweight vehicles from the FMCSR is analogous to the granting of a certificate of exemption under the MCA because although both Acts may be rescinded, they both remove a class of employees from the DOT’s power to regulate. Thus, they contend that the DOT in effect has denied itself section 3102 power by determining that the regulation of lightweight motor vehicles is not needed to promote safety of operation.
However, the DOT expressly retained its power to regulate lightweight vehicles. In a statement issued in May of 1988, in connection with the publication of the DOT’s Final Rule pertaining to the FMCSR, the FHWA explained the underlying rationale for not regulating lightweight vehicles at this time.
Although the FHWA retains its authority to regulate lighter weight vehicles in the interest of safety (49 U.S.C. § 3Í02), the FHWA does not believe that such Federal regulation is warranted at this time.
See 53 Fed.Reg. 18,042, 18,044 (1988).
Next, the plaintiffs rely on cases from the Ninth Circuit for the proposition that where the DOT exempts a category of employees from the MCA, the FLSA applies. See Jones v. Giles, 741 F.2d 245, 249 (9th Cir.1984); Newhouse v. Robert’s Ilima Tours, Inc., 708 F.2d 436 (9th Cir.1983). In Newhouse, 708 F.2d at 439-40, the court held that because the plaintiffs, Hawaiian tour company drivers, had been granted a certificate of exemption by the ICC from compliance with the MCA, they became subject to the FLSA until the ICC revoked or conditioned the certificate of exemption. In Jones, 741 F.2d at 249, the court held that the plaintiffs, Washington state ambulance drivers, were not subject to the authority of the DOT because the ICC had exempted ambulance services from the MCA, Lonnie W. Dennis, 63 M.C.C. 66 (1954), and the DOT later incorporated this exemption into its interpretation of the FMCSR, 42 Fed.Reg. 60,080 (1977); 40 Fed. Reg. 50,677 (1975). In both of these cases, the'ICC affirmatively exempted a group of employees. Here, however, the DOT has neither granted any specific exemption nor has it expressly disclaimed jurisdiction over employees of motor private carriers.
The plaintiffs claim that the DOT's exemption by affirmative action differs from a failure to promulgate regulations.
A mere failure to promulgate regulations or to enforce regulations which have been promulgated is not sufficient to take an employee beyond the [DOT’s power to regulate qualifications and maximum hours of service of employees under-section 3102]'... On the other hand, when employees are placed by affirmative action of the DOT ... beyond the scope of the regulations promulgated under the relevant power, the employees are no longer subject to the relevant power — for so long as that regulation or exempting action remains in effect under the DTA.
Brock v. Pacific Vacuum Truck Co., 106 LC ¶ 34,892, 44,871, 27 WH 1617, 1621, 1987 WL 13,666 (C.D.Cal.1987). In Brock, the Secretary of Transportation had concluded that its regulations under the MCA went to the limit of its statutory authority and thus believed that any person not covered by the regulation necessarily fell beyond the scope of the statute.
Recently, the Second Circuit Court of Appeals, in a case similar to this, observed that Brock turned on deference to the Secretary’s interpretation of the scope of the MCA. Martin v. Coyne Int’l Enter. *416Corp., 966 F.2d 61, 64 (2nd Cir.1992).9 We agree with the Martin court that to the extent Brock suggests that where a group of employees has been left out of a regulation, the Secretary then lacks the power to regulate those employee, Brock is impossible to reconcile with the Supreme Court’s earlier cases of Southland, Levinson, and McComb. Id. at 64.
The amicus, the Secretary of Labor, acknowledges that the DOT may choose to exercise its regulatory power over passenger and lightweight vehicles but argues that until the DOT does, it lacks regulatory power over such vehicles. In United States v. Nixon, 418 U.S. 683, 694-96, 94 S.Ct. 3090, 3100-02, 41 L.Ed.2d 1039 (1974), the Supreme Court held that although the Attorney General originally may have had power to represent the government in matters concerning the invocation of executive privilege, he delegated that power by regulation to the Special Prosecutor and lacked the power until he rescinded or amended the regulation; accord United States ex rel. Accardi v. Shaughnessy, 347 U.S. 260, 267, 74 S.Ct. 499, 503, 98 L.Ed. 681 (1954). These cases are inapposite because here the DOT has not delegated its power but rather has chosen not to exercise it. The plaintiffs have failed to show that the DOT interpreted the scope of its authority under the MCA not to cover commercial operations involving passenger automobiles. Rather, the DOT’s failure to exercise its regulatory power over passenger cars in commercial operation and other lightweight motor vehicles appears to stem from Congress’ directive that the DOT focus on vehicles weighing more than 10,000 pounds.
The amicus further admits that a literal reading of the MCA subjects the plaintiffs to the DOT’s regulatory power. The ami-cus asks that we interpret the word “power” to mean “power that is actually used” rather than “power that might someday be used”. However, “[i]t is not necessary, as a condition precedent, to find that the Commission has exercised, or should exercise, such power by actually establishing qualifications and maximum hours of service.... The existence of the power is enough.” Levinson, 330 U.S. at 678, 67 S.Ct. at 946 (emphasis added); accord Morris v. McComb, 332 U.S. at 434, 68 S.Ct. at 137; Martin, 966 F.2d at 62-63; Marshall v. Union Pac. Motor Freight Co., 650 F.2d 1085, 1089 (9th Cir.1981); Brennan v. Schwerman Trucking Co., 540 F.2d 1200, 1203 (4th Cir.1976). We conclude that the DOT has retained its power to regulate employees of motor private carriers who drive lightweight passenger vehicles in interstate commerce.
III.
Having decided that DOT’s election not to regulate lightweight and passenger vehicles does not strip it of its power to establish maximum hours and qualifications for private motor carriers, we must determine whether the district court erred in concluding that the plaintiffs fall within the MCA exemption. The Supreme Court has interpreted the word “employees” in section 304 to mean those employees whose duties affect the safety of operation. See American Trucking Ass’ns, 310 U.S. at 553, 60 S.Ct. at 1069. It is arguable that a lesser safety-related limitation should be placed upon the MCA’s use of the term “private carrier” when examining the plaintiffs’ effect on the safety of CableData’s transportation operation. As stated by the district court, in enacting the MCA, Congress apparently was more concerned at the time with the dangers of commercial trucks and buses rather than of personal automobiles. Friedrich v. United States Computer Serv., 787 F.Supp. 449, 456 (E.D.Pa.1991).
The Supreme Court has recognized a de minimis exception to the application of the MCA. In Pyramid Motor Freight Corp. v. Ispass, 330 U.S. 695, 708, 67 S.Ct. 954, 960, 91 L.Ed. 1184 (1947), the Court held that although loaders of freight affect the safety of operation and thus fall within the MCA, persons who merely handle *417freight before or after loading perform tasks that may be too “trivial, casual or occasional” to affect safety and bring them under the MCA’s authority. The district court here rejected a de minimis exception, however, because the MCA specifically defines motor private carrier. Id. at 18. The MCA does not limit motor private carriers to those who ship large amounts of property or ship property as their principal business; it merely requires that they transport property “to further a commercial enterprise.” We agree that the safety effect of the plaintiffs’ activities is not de minimis.10
In a similar vein, the MCA does not define “property” and it is arguable that the tools, parts, and equipment the plaintiffs transported were so trivial or insubstantial that they did not constitute property within the meaning of the MCA.11 However, the DOL’s Field Operations Handbook states that the DOT has jurisdiction over private carriers when “the transportation of property, regardless of its bulk or weight, is the primary purpose of an interstate trip by a private carrier, or if the transportation of such property is a distinct and definite reason for the trip along with the transportation of persons.” Id. at 24a05(c). In an opinion letter of the Wage-Hour Administrator addressing similar facts, the DOL opined that service engineers employed by a national distributor of scientific and medical instrumentation fell within the MCA exemption. See Opinion Letter No. 1323 (WP-271) (June 5, 1974). The letter stated:
[I]t would appear that the reason these service managers carry large quantities of service parts on their trips throughout the various States in their territory is to insure that they are able to perform whatever technical repair services may be required. Accordingly, the transportation of such property by motor vehicle in interstate commerce is a distinct and definite reason for the trip by these service managers and that in those cases where, as a regular practice, a service manager transports this equipment across State lines they would qualify for the overtime exemption under section 13(b)(1) of the Act.
Although the DOT is not bound by the DOL’s interpretation of the DOT’S authority under the overtime exemption, the above reasoning is persuasive. Because the plaintiffs transported tools, parts, and equipment without which they could not have performed their duties for CableData and the services required of it by its customers, the transportation of those items was an independent and essential reason for their service trips. Thus the tools, parts, and equipment constituted property within the meaning of the MCA.
This conclusion does not give employers carte blanche authority to relieve themselves of the FLSA overtime requirements. The DOT’s jurisdiction over employees of private motor carriers is limited to those who affect the safety of operation. The DOT has authority over drivers only where the employees regularly travel interstate or reasonably are expected to do interstate driving. See Dole v. Circle “A” Constr., Inc., 738 F.Supp. 1313, 1323 (D.Idaho 1990) (DOT has jurisdiction over all employee-drivers if all drivers are subject to the indiscriminate distribution of interstate hauls); DOT Notice of Interpretation, 46 Fed.Reg. 37,902, 87,903 (1981) (DOT has jurisdiction over “a driver who is called on, or is subject to being called on, to drive in interstate commerce as part of the driver’s regular employment ... [or] because of company policy and activity, the driver could reasonably be expected to do interstate driving”).
*418Nonetheless, motor vehicle operators can come within the terms of the MCA exemption even though they may perform other duties than driving.
[I]t is not a question of fundamental concern whether or not it is the larger or the smaller fraction of the employee’s time or activities that is devoted to safety work. It is the character of the activities rather than the proportion of either the employee’s time or of his activities that determines the actual need for the Commission’s power to establish reasonable requirements with respect to qualifications, maximum hours of service, safety of operation and equipment.
Levinson, 330 U.S. at 674-75, 67 S.Ct. at 944.
Thus, it is not determinative that the plaintiffs may have devoted more time to field service than to the transportation of property. Because their interstate operations affected safety on the highways, the plaintiffs fell within the MCA even though they were not employed primarily as carriers. See, e.g., Peraro v. Chemlawn Services Corp., 692 F.Supp. 109, 111, 114 (D.Conn.1988) (carpet cleaners who drive specially equipped trucks to clean carpets covered by MCA); Sinclair, 447 F.Supp. at 10-11 (employees who drive company-furnished pickups with tools, equipment, and supplies to service and maintain pipeline system covered by MCA); Harshman v. Well Serv., Inc., 248 F.Supp. 953, 958-59 (W.D.Pa.1964) (employees who drive cement pumping trucks to service and repair gas wells covered by MCA), aff'd per curiam, 355 F.2d 206 (3d Cir.1965). Nor is it significant that the plaintiffs did not drive Cabledata’s vehicles. See DOL Wage & Hour Field Operations Handbook at 24a05(d) (May 13, 1982) (employee of private carrier who transports property in interstate travel in personal vehicle is subject to otherwise applicable MCA exemption).
The dissent acknowledges that tool kits were necessary to the performance of plaintiffs’ job duties, dissenting op. at 420, but suggests that the transportation of the kits and replacement parts in personal vehicles to customer sites was ancillary because plaintiffs “could have easily mailed the tool kits and replacement parts to customers sites.” Id. This reasoning is predicated upon two assumptions, both of which are unrealistic and impractical. First, it assumes that the packaging of the kits and replacement parts is neither inconvenient nor expensive, that mail deliveries are timely made, and that the field engineers can effectively coordinate the needs of a highly sensitive cable television industry for repair and maintenance of its computer equipment with unpredictable mail delivery. Second, it assumes that the customers will bear the unnecessary expense and inconvenience of having these items mailed when they can be transported without charge or delay by the field engineers in their automobiles when they travel to perform their services.
Finally, the plaintiffs contend that although the district court in this case found it unlikely that Congress contemplated operations such as CableData’s when enacting and reenacting the MCA, the court failed to carry out congressional intent. The district court observed that given the more recent enactment of the MCSA and its directives that the DOT focus on commercial motor vehicles weighing more than 10,000 pounds, “it is equally unlikely that the DOT will use the regulatory authority of § 3102 to establish maximum hours of employment that cover CableData’s field engineers.” Friedrich, 787 F.Supp. at 457. The court concluded, however, that because the language of the MCA gives the DOT that authority and the DOT has not specifically determined otherwise, courts must follow the statute unless Congress acts to limit the DOT’S power over commercial carriers by personal automobile or the DOT more clearly determines that it is not authorized to regulate such vehicles. Id.
In interpreting a statute, we must start with the language of the statute itself. Barnes v. Cohen, 749 F.2d 1009, 1013 (3d Cir.1984), cert. denied, 471 U.S. 1061, 105 S.Ct. 2126, 85 L.Ed.2d 490 (1985). Although a statute should be interpreted in a fashion that does not defeat the congres*419sional purpose, Public Citizen v. United States Dep’t of Justice, 491 U.S. 440, 454-55, 109 S.Ct. 2558, 2266-67, 105 L.Ed.2d 377 (1989), a court may not rewrite an unambiguous law. Even if the court does not believe that Congress intended a specific outcome when it drafted a law, the court “must give effect to the unambiguously expressed intent of Congress.” Friends of Sakonnet v. Dutra, 738 F.Supp. 623, 633 (D.R.I.1990) (citing Chevron, U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 842-43, 104 S.Ct. 2778, 2781, 81 L.Ed.2d 694 (1984)).
Facially, it may seem implausible to deny the DOL regulatory power to impose fair labor standards over drivers of passenger vehicles in interstate commerce. However, the legislature and not the judicial branch of government has the responsibility to expand the DOL’s regulatory power. We consider it significant that as late as 1983 and 1984, when Congress renewed its concern over the safety of motor carriers in interstate commerce, it did not exempt lightweight vehicles or passenger cars from the regulatory power of the DOT. Pursuant to the tenets of statutory interpretation, we see no error in the district court’s determination that it lacked the authority to limit the DOT’s power to regulate the plaintiffs.
IV.
In summary, we conclude that the DOT retains the power to establish maximum hours and qualifications for employees of motor private carriers who drive lightweight vehicles in interstate commerce. The DOT has not delegated or forfeited this power simply by choosing not to exercise it. Because the plaintiffs literally fell within the MCA exemption and neither Congress nor the DOT has taken action to the contrary, we hold that employees operating passenger automobiles in interstate activities which require them to transport property essential to their job duties come within the reach of the Federal Motor Carrier Act as amended and are therefore exempt from the FLSA’s overtime compensation requirements.
Accordingly, the judgments of the district court will be affirmed.
. Subject matter jurisdiction of this controversy exists under section 16(b) of the FLSA and under the provisions of 28 U.S.C. § 1337 relating to a civil action arising under an Act of Congress regulating commerce and 28 U.S.C. § 1331. There is diversity of citizenship between the parties.
. The court reserved decision with respect to the plaintiffs’ state law claims under the PMWA and the WPCL. Also not before this court is the district court's denial of the plaintiffs’ motion for preliminary injunction, alleging retaliation by CableData in violation of the FLSA, 29 U.S.C. § 215(a)(3), and the district court’s denial of CableData's motion for summary judgment concerning the fluctuating workweek defense.
. Although the brief is helpful, the DOT, not the United States Department of Labor (DOL), is the agency charged with the administration and interpretation of the MCA. See Levinson v. Spector Motor Serv., 330 U.S. 649, 676-77, 67 S.Ct. 931, 945, 91 L.Ed. 1158 (1947). The DOL cannot interpret the DOT’S power under the MCA to expand the jurisdiction of the FLSA. Id. at 684, 67 S.Ct. at 948. Deference should be accorded to the reasonable construction of the agency to which Congress entrusted responsibility, and not to another agency whose interest is collateral. Federal Labor Relations Authority v. United States Dep’t of Navy, 966 F.2d 747, 764 (3d Cir.1992).
. "Motor carriers” include both "motor common carriers" and "motor contract carriers.” See 49 U.S.C. § 10102(13). Motor common carriers are those that hold themselves out to the general public to provide motor vehicle transportation for compensation. Id. at § 10102(14). Motor contract carriers are those that provide transportation of persons or property in accord with continuing agreements. Id. at § 10102(15).
. Section 3102 provides in part:
(b) The Secretary of Transportation may prescribe requirements for—
(1) qualifications and maximum hours of service of employees of, and safety of operation and equipment of, a motor carrier; and
(2) qualifications and maximum hours of service of employees of, and standards of equipment of, a motor private carrier, when needed to promote safety of operation.
See 49 U.S.C. § 3102(b).
. The plaintiffs contend that the MCA exemption would apply only when they personally transported equipment across state lines by motor vehicle. However, the parts and equipment used by the plaintiffs were distributed in a company-wide interstate network system. Under the “continuity of movement” principle of interstate commerce, the MCA exemption is applicable. See 29 C.F.R. § 782.7(b)(1) (1991) (interstate commerce under MCA includes, inter alia, transportation of property which moves in interstate commerce even though vehicles operate solely intrastate); Morris v. McComb, 332 U.S. 422, 434, 68 S.Ct. 131, 137, 92 L.Ed. 44 (1947) (ICC has power to regulate pursuant to section 304 of MCA where 4% of driver’s routes cross state lines). Although the plaintiffs here transported some property across state lines by airplane, they continued the transportation in rental cars.
. The FHWA is an administration in the DOT that has authority to carry out the duties of the Secretary of Transportation with respect to motor carrier safety. 49 U.S.C. §§ 104(a), (c).
. Where Congress reenacts a statute without substantive change, it generally is presumed to be aware of any administrative or judicial interpretations and to adopt those interpretations by reenactment. See Lorillard v. Pons, 434 U.S. 575, 580-81, 98 S.Ct. 866, 870, 55 L.Ed.2d 40 (1978). Reenactment without change gives such interpretations the force of law. See Helvering v. R.J. Reynolds Tobacco Co., 306 U.S. 110, 115, 59 S.Ct. 423, 426, 83 L.Ed. 536 (1939).
. The Martin court held that the DOT had retained its power to regulate drivers who deliver laundry in trucks weighing 10,000 pounds or less and thus the plaintiff-drivers were not subject to the FLSA overtime requirements. Martin, 966 F.2d at 64.
. A number of courts have held that drivers should seldom, if ever, fall within this de minimis exception. See Levinson, 330 U.S. at 677-78, 67 S.Ct. at 945-46; Crooker v. Sexton Motors, Inc., 469 F.2d 206, 210 (1st Cir.1972); Sinclair v. Beacon Gasoline Co., 447 F.Supp. 5, 11 (W.D.La.1976), aff'd, 571 F.2d 978 (5th Cir.1978). Note that the MCA exemption is not limited to drivers. See, e.g., Brennan, 540 F.2d at 1204 (MCA exemption extends to private carriers’ mechanics).
. The parties stipulated that a field engineer's tool kit contains approximately 75 tools and weighs approximately 35 pounds.