LaFontaine placed his resignation in the hands of the governor-general, who accepted it with regret. No doubt the former had deeply felt the loss of his able colleague, and was alive to the growing belief among the Liberal politicians of Upper Canada that the government was not proceeding fast enough in carrying out the reforms which they considered necessary. LaFontaine had become a Conservative as is usual with men after some experience of the responsibilities of public administration, and probably felt that he had better retire before he lost his influence with his party, and before the elements of disintegration that were forming within it had fully developed. After his retirement he returned to the practice of law, and in 1853 he became chief justice of the court of appeal of Lower Canada on the death of Sir James Stuart. At the same time he received from the Crown the honour of a baronetcy, which was also conferred on the chief justice of Upper Canada, Sir John Beverley Robinson.
Political historians justly place LaFontaine in the first rank of Canadian statesmen on account of his extensive knowledge, his sound judgment, his breadth of view, his firmness in political crises, and above all his desire to promote the best interests of his countrymen on those principles of compromise and conciliation which alone can bind together the distinct nationalities and creeds of a country peopled like Canada. As a judge he was dignified, learned and impartial. His judicial decisions were distinguished by the same lucidity which was conspicuous in his parliamentary addresses. He died ten years later than the great Upper Canadian, whose honoured name must be always associated with his own in the annals of a memorable epoch, when the principles of responsible government were at last, after years of perplexity and trouble, carried out in their entirety, and when the French Canadians had come to recognize as a truth that under no other system would it have been possible for them to obtain that influence in the public councils to which they were fully entitled, or to reconcile and unite the diverse interests of a great province, divided by the Ottawa river into two sections, the one French and Roman Catholic, and the other English and Protestant.