His employer was David Webster, London merchant of a sugar trading house, with family connections through the Wedderburn baronets to the slave plantations of Jamaica.

He describes it vividly in his memoirs forty years later, concluding, "After hearing this debate, I could no longer have been content with being 'Moderator of the General Assembly [of the Church of Scotland]'.".

The second was called for by the preference which the common law gave to a distant collateral over the brother of the half-blood of the first purchaser; the fourth conferred an indefeasible title on adverse possession for twenty years (a term shortened by Lord Cairns in 1875 to twelve years); the fifth reduced the number of witnesses required by law to attest wills, and removed the distinction which existed in this respect between freeholds and copyholds; the last freed an innocent debtor from imprisonment only before final judgment (or on what was termed mesne process), but the principle stated by Campbell that only fraudulent debtors should be imprisoned was ultimately given effect to for England and Wales in 1869.

[7]In 1840 Campbell conducted the prosecution against John Frost, one of the three Chartist leaders who attacked the town of Newport, all of whom were found guilty of high treason.

While composing his biographical works Campbell remained active in the House of Lords and spoke frequently against legislation proposed by Sir Robert Peel's government.

Although well versed in the common law, Campbell was criticised for attempting to influence juries in their estimate of the credibility of evidence, as was seen in the 1852 Achilli case.

He assisted in the reforms of special pleading at Westminster, and had a recognised place with Brougham and Lyndhurst in legal discussions in the House of Lords.

Campbell was taken by the analogy between the two situations, famously referring to the London pornography trade as "a sale of poison more deadly than prussic acid, strychnine or arsenic".

[11] Campbell proposed a bill to restrict the sale of pornography; giving statutory powers of destruction would allow for a much more effective degree of prosecution.

The bill was controversial at the time, receiving strong opposition from both Houses of Parliament, and was passed on the assurance by Campbell, in his capacity of Lord Chief Justice, that it was "... intended to apply exclusively to works written for the single purpose of corrupting the morals of youth and of a nature calculated to shock the common feelings of decency in any well-regulated mind."

[12] In 1859 Campbell was made Lord High Chancellor of Great Britain, possibly on the understanding that Bethell should succeed as soon as he could be spared from the House of Commons.

In 1836 Lady Campbell was created (in her own right) Baroness Stratheden, of Cupar in the County of Fife, in recognition of her husband's withdrawal of his claim to the office of Master of the Rolls; she died in March 1860, aged 63.