Tom C. Clark,
Norton Company v. Department of Revenue of Illinois…
“ The general rule, applicable here, is that a taxpayer claiming immunity from a tax has the burden of establishing his exemption.' Petitioner has failed to meet this burden. In fact Illinois has shown that petitioner's Chicago office is its only source of customer relationship in Illinois; that the Chicago office provides the sole means through which petitioner can be reached with process by Illinois courts in the event a customer is aggrieved; that the local office affords service to machines after sale, as well as replacement of machines which are defective ”
