the basis of being part of a larger income, and therefore on a higher graduated scale, the mortgagor pays in respect of the mortgagee's income tax only such sum as he would pay if his own income amounted only to the sum he pays for interest.
The first thing is to interpret the enactment. It has been argued that its terms, particularly the word "obligation," are to be read in a popular sense. Its subject matter, however, is a "mortgage" of land, which is a term of art, and the expressions which are used with respect to the mortgage are legal and technical terms, namely, "covenant," "stipulation," "imposing the obligation" and
interest to be paid under the mortgage." It is a cardinal rule of interpretation that technical words must have their legal effect unless the contrary is made perfectly clear. It was SO held by the Privy Council in Lalit Mohun Singh Roy v. Chukkun Lal Roy 1, which was the case of a will. The principle applies à fortiori to a Statute (see Burton v. Reevell 2; The Queen v. Commissioners of Income Tax 3, and Attorney-General v. Glossop 4 ). In the last- mentioned case Collins M.R. applied the principle to the Finance Acts, notwithstanding an argument very similar to that addressed to us, that words primarily technical should be read from a popular standpoint. This principle applies with "special cogency," said Lord Robertson in Lord Advocate v. Stewart 5, "when the words in question present only legal conceptions. The popular use of such words does not represent the primary meaning of the words, but some half understanding of them." I therefore read the governing portion of the section in a legal sense. So reading it, we must, in order to assent to the appellants' contention, find a stipulation having the
effect " of imposing on the appellants the obligation of paying income tax on the interest to be paid under the mortgage.
Turning to the mortgage, it is one made before the commencement of the Act. The principal sum is £9,000, and by the first clause of the mortgage the mortgagors covenant to repay that sum and interest "at the rate of five pounds fifteen shillings per centum per annum reducible as hereinafter mentioned." The "herein- after" consists of clause 7, which says: "Provided always and it is
124 Cale., at p. 846 L.R. 24 Ind. 216 M. &W., 307, at p. 309. 322 Q.B.D., 296, at p. 309. App., 76. 4(1907) 1 K.B., 163, at p. 172. 5(1902) A.C., 344, at p. 356.