Arthur Dewar, later Lord Dewar, was a Scottish politician and judge, who served as a Liberal Member of Parliament for Edinburgh South as well as Solicitor General for Scotland and later a Senator of the College of Justice.
He was born in Perth, the fourth son of John Dewar, Sr. the distiller and founder of John Dewar & Sons. His brothers, Thomas and John, would run the family business. He married Lettie Dalrymple in 1892, with whom he would have one daughter.
He was educated at Perth Academy and then at Edinburgh University, graduating in 1882. He was admitted to the Scottish Bar in 1885, and in 1892 was appointed the Advocate-Depute for the Glasgow circuit, a minor governmental post, which he held until 1895 when the Conservative Party came into power.
In an 1899 by-election he was elected as the Member of Parliament for Edinburgh South, defeating Major-General A.G. Wauchope, but was defeated himself in the 1900 general election by Sir Andrew Agnew. He stood again in the 1906 general election, where he won the seat. He had been made King's Counsel in 1904, and served as Solicitor General for Scotland from 1909-1910.
He was re-elected in the January 1910 general election, but in April was appointed a Senator of the College of Justice in 1910, and resigned from the Commons. He took the judicial title of Lord Dewar, and served in the post until his death.