Motor vehicle definition and incorporated taxation provisions determine when mining vehicles need registration and escape tax.

The article explains that dumpers and rockers may be treated as motor vehicles if their construction makes them suitable for road use, even when designed for mining operations, while tractors with compressed-air attachments were treated differently on the facts. It also notes that, for a State motor vehicle taxation law adopting another statute's definition by incorporation, later amendments to the parent Act do not automatically expand the tax base unless the State law is amended. Vehicles used solely within enclosed mining premises, where the public has no right of access, fall outside the tax net under that construction.

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Issues: (i) Whether dumpers, rockers and tractors are motor vehicles within the meaning of the Motor Vehicles Act and liable to registration; (ii) Whether, for the purposes of the Motor Vehicles Taxation Act, the definition of motor vehicle was frozen at the time of incorporation and whether such vehicles, when used solely within enclosed mining premises, are taxable.

Issue (i): Whether dumpers, rockers and tractors are motor vehicles within the meaning of the Motor Vehicles Act and liable to registration.

Analysis: The definition of motor vehicle was read as requiring a mechanically propelled vehicle adapted for use upon roads, that is, suitable or fit for use on roads. Vehicles are not excluded merely because they are heavy or specially designed for mining work if their nature and construction make them capable of road use. On the evidence, dumpers and rockers retained road suitability, while tractors with compressed-air attachments were treated differently on the facts.

Conclusion: Dumpers and rockers were motor vehicles and liable to registration, while the tractairs were not registerable on the facts found.

Issue (ii): Whether, for the purposes of the Motor Vehicles Taxation Act, the definition of motor vehicle was frozen at the time of incorporation and whether such vehicles, when used solely within enclosed mining premises, are taxable.

Analysis: The taxing statute adopted the definition of motor vehicle by incorporation by reference, so subsequent amendments to the parent motor vehicle legislation did not enlarge the tax base under the State Act. The taxing power was treated as compensatory and connected with vehicles using roads. The evidence showed that the relevant machines were used only within controlled mining areas where the public had no right of access, which brought them within the exclusion for vehicles used solely upon the premises of the owner or within enclosed premises.

Conclusion: The post-1956 amended definition did not govern the taxation statute, and dumpers and rockers used solely within enclosed premises were not taxable, while tractairs were neither registerable nor taxable.

Final Conclusion: The challenge to tax liability succeeded in part, the vehicles confined to enclosed mining premises escaping taxation, and the constitutional challenge became academic.

Ratio Decidendi: Where a State taxing statute incorporates by reference the definition in another Act, the incorporated definition remains as it stood at the time of incorporation unless the State law is itself amended, and vehicles used only within enclosed premises are outside the tax net notwithstanding later amendments to the parent enactment.

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