INDIRECT ENCROACHMENT ON FEDERAL AUTHORITY 677 absence of special circumstances, an excise or occupation tax on a local business may be based on all the property used in that business even though that property is also used in interstate business and is also subjected to an ad valorem property tax.^^" But it may readily be conceived that special circumstances may make such a measure of an excise or occupation tax a very real burden on interstate commerce. It is apparent that when such taxes are imposed on specially selected enterprises, they may in fact constitute serious discriminations against interstate commerce. All the property may be used for local as well as interstate commerce and yet the latter constitute by far the greater part of the total business. If a state is allowed free range in prescribing the rate of levy on such a property base, it may do quite as serious an injury to interstate commerce as it could inflict by basing the tax on total capital stock. Though the court may as a general rule accept property employed in local business as the proper measure of an occupation tax on that business, it must always have at hand its doctrine that every case depends on its own circumstances and must be ready to find the special circumstances that take the case out of the general rule. It must be impossible to lay down any general rule as to what is a proper amount to impose as a specific tax on a local business that is combined with an interstate business. All that can be said is that by and large the punishment must fit the crime. One thousand dollars may not have been too much for Virginia to demand of the Railway Signal Company in view of its contracts within the state. Yet the same sum based on the same capital stock might prevent it from bidding on small contracts within the state. Where the performance of the contract calls for interstate as well as local enterprise, a fee out of all proportion to the consideration for the contract may stand as an absolute bar to the particular interstate commerce. This is the vice of all occupation or business taxes that are not measured by the value of what is being taxed. The vice is particularly noxious in the case of corporations not regularly en- gaged in business within the state, but which merely enter to do occasional jobs. The vice does not seem to have manifested itself "" In Amos v. Postal Telegraph-Cable Co. (Fla.), 80 So. 293 (1918), the supreme court of Florida held that a state license fee or occupational tax measured by property within the state should exclude from the computation property employed exclusively in interstate commerce. The opinion regarded the construction as necessary to save the tax from being an unconstitutional regulation of interstate commerce.
