The Crown Suits Act 1769 (9 Geo. III., c. 16) was an Act of the Parliament of Great Britain passed in 1769.
In 1765 William Cavendish-Bentinck, 3rd Duke of Portland, brought against James Lowther, 1st Earl of Lonsdale and the corporation of Carlisle bills in chancery for the perpetuation of testimony, believing that he was the owner of a fishery on the River Eden in right of the socage manor of Carlisle but because of the type of fishing carried on by the defendants it had become useless. However Lonsdale's team discovered in the original grant from William III to the first Duke of Portland that the socage manor of Carlisle and the forest of Inglewood had been expressly omitted in the grant. But an Act from the reign of James I had laid down that lands in undisturbed possession of over sixty years no one could challenge a title except the Crown. In 1767 Lonsdale therefore successfully petitioned the Treasury for a grant of Crown interest in the two properties "for three lives, on such terms as to their lordships should seem meet". Portland's allies claimed no land was safe if the legal maxim Nullum tempus occurrit regi ("No time runs against the king") was to be implemented so therefore in February 1767 Sir George Savile introduced a Bill to abrogate the legal maximum and to abolish Lonsdale's rights. This was defeated by 134 votes to 114. In 1768 another Bill was introduced, this time including a clause which excluded all Crown grants made before 1 January 1769 from the operation of the Bill unless the grantees prosecuted their claims within one year. With the passing of this Act Lonsdale at once filed a bill against Portland and evicted three hundred tenants. However the Court of Exchequer ruled against Lonsdale on the grounds that the grant was unlawful under the provisions of the Crown Lands Act 1702 because of the insufficiency of the rent reserved by the Crown. Portland's title to the socage manor of Carlisle and Inglewood forest was never tried and he eventually sold the properties to the Duke of Devonshire in 1787.