The House of Lords had some of the greatest legal minds in the world. The law lords therein constituted the highest legal authorities in the British Empire. It was not by coincidence, therefore, that Lord Derby, who moved a censure resolution against the government on account of the bombardment of Canton, began the China debate on 24 February 1857 by appealing to their lordships ‘to deal with the question in a purely judicial spirit’.

It is fascinating to see their lordships thresh out the legal complexities of the case of the Arrow, and thence what some of them regarded as the origins of the war. That protracted debate may be boiled down to the following major issues: whether the British flag was flying; whether an insult was intended; whether the Arrow was entitled to fly the British flag; the expiry of the Arrow's register; abuses of the colonial ordinance whereby the Arrow's register had been granted; whether the actions of Parkes, Seymour, and Bowring were justified; whether Bowring had acted in the best interest of the nation; the Canton City question; the right to make war; whether it was a just war; whether the debate was motivated by justice and humanity or by party politics; and how important the China trade was.

One may put these various issues into three main categories: legal technicalities, issues of justice and humanity, and trading matters.