On 6 May 1917 Peden was given a life appointment to the
New South Wales Legislative Council by Governor Sir Gerald Strickland on the advice of Premier
William Holman, taking up his seat as a
Nationalist on 17 July 1917. Appointed by Governor
Sir Dudley de Chair as
President of the Legislative Council from 1929, Peden was a leader in the opposition to
Labor Premier
Jack Lang's attempts to abolish the council. He drafted section 7A of the Constitution Act of 1902, added by amendment in 1929, to ensure that the council could not be abolished, nor its powers be altered, except through the expression of the people through a referendum. Lang's inability to gain control in the Upper House obstructed his legislative program and, following a long-standing Labor policy to abolish the Legislative Council (Queensland Labor had been
similarly successful in 1922), in November 1930, claiming a mandate to abolish the Council, Lang's Labor MLCs put forward two bills, one to repeal section 7A and the other to abolish the Council. Lang had requested Governor
Sir Philip Game and his predecessor, De Chair, for sufficient appointments to the Legislative Council in order to pass these bills, but on each occasion was met with refusal. Believing that a
referendum was necessary before the bills could become law as per Peden's legal reasoning, the Legislative Council permitted the bills to pass without a division on 10 December. Lang then announced his intention of presenting the bills for Game's
Royal assent without a referendum. The following day, two members of the Legislative Council,
Thomas Playfair and
Arthur Trethowan, applied for and were granted an injunction preventing Lang and his ministers from presenting the bills to the Governor without having held a referendum. Peden, despite being named as the first defendant, did not defend the case as he was convinced of section 7A's validity under the
Colonial Laws Validity Act 1865. On 23 December the
Supreme Court of New South Wales in the case of
Trethowan v Peden, upheld the injunction and ordered the government not to present bills to abolish the council for royal assent, unless ratified by the electors in a referendum. Lang immediately prepared an appeal to the
High Court of Australia. In the case of
Attorney-General (New South Wales) v Trethowan, the appeal was rejected by a majority of the court. Lang then appealed this decision to the
Judicial Committee of the Privy Council in London, however the Privy Council delayed hearing the appeal until April 1932. The appeal was finally resolved with the judgment of the Judicial Committee of the Privy Council on 31 May 1932 which dismissed the appeal by the
Government of New South Wales. The bills repealing Section 7A and abolishing the Legislative Council could not therefore be presented to the Governor for assent until they had been passed in a referendum. and was the first elected president of the council. He did not stand for reelection on the expiry of his term, retiring in 1946. ==Later life==