The Court affirmed and applied the principles of treaty interpretation from earlier cases and held that oral agreements are as much a part of a treaty as the written terms. The historical and cultural contexts have to be taken into account in ascertaining what constitutes the treaty. In this case, a Mi'kmaq promise in a 1760-61 treaty to trade only at truck houses (trading posts) established by the British necessarily implied a right to acquire natural products, such as fish, for trade in order to obtain a moderate livelihood. Like Aboriginal rights, treaty rights are subject to justifiable infringement, by application of the Sparrow test (Period 8 above), as elaborated on in R. v. Gladstone (1996).