The foundation of the government position was that the United States could legitimately offset the interest on subsidy bonds which it was paying currently against the sums due the bond-aided railroads for government transportation. The reply of the court was, first, that the general principles of “set-off” did not apply in the case at bar; and second, that the United States had no claim in any event because the law did not require the Union Pacific (and the same principles applied to other bond-aided railroads) to meet the interest charges on the government advances until the maturity of the bond.[526] A later case added the ruling that the United States had in the matter only the right of a creditor growing out of contract, and could not fall back upon its sovereign rights in order to protect its financial claim.[527] Not only did the Supreme Court decide completely in favor of the companies in the important matter of “set-off,” and in that relating to the date upon which the Pacific railroads became liable for the payment of accruing interest on the subsidy bonds, but it diminished also the sinking fund payments of the companies by holding that under existing legislation it was proper for the companies, in calculating net earnings, to deduct from gross earnings expenses incurred for enlarging and improving their property. The particular account involved was that of expenditure for station buildings, shops, and fixtures. Such expenditures are not ordinarily charged to operating expenses, and the court admitted that “theoretically” they should not be so charged. The practice was nevertheless justified on the ground of general policy, as likely to encourage a liberal application of earnings to improvements. The same decision also authorized the Central and the Union Pacific to deduct interest on first mortgage bonds from earnings before computing the 5 per cent of net earnings which was to be credited to the sinking fund. This ruling was defended as a legitimate consequence of the concession of priority to the first mortgage bonds.[528] Need of Governmental Action