John Louis Carleton was born in Saint John , New Brunswick, in 1861, the son of William Carleton and Bridget O'Connor. Both families were of Irish ancestry. John Carleton was educated in the public education system and later at the School of the Christian Brothers in Saint John. He then studied law in the offices of Weldon & McLean and in the offices of Allen and Chandler. Carleton was admitted to the Bar of New Brunswick as an attorney in 1882 and as a barrister in 1892.

Carleton established a law practice in Saint John and in 1886 was appointed referee in Equity. Carleton was later appointed as a reporter for the Supreme Court of New Brunswick. In 1886, he married Theresa Gertrude Sharkey, daughter of Peter Sharkey of Saint John. John Louis Carleton was a member of several fraternal and benevolent societies. At the 22 October 1892 general election for the House of Assembly, he was an unsuccessful Liberal candidate for a Saint John city seat. In 1900, the first of two daughters, Blanid, was born to Mr. and Mrs. Carleton. In 1904, her sister, Mary Theresa, was born.

In 1904, Mr. Carleton was appointed county court judge for the district comprising the counties of Carleton, Victoria, and Madawaska following the retirement of James G. Stevens. In May of that year, Judge Carleton established an office in the Opera House Block in Woodstock. By September of 1904, Judge and Mrs. Carleton were living in the D. A. Grant residence on Victoria Terrace in Woodstock, after having first lived in the Carlisle Hotel. In 1908, Theresa Gertrude Carleton (nee Sharkey) died, leaving Judge Carleton with two very young daughters. On 7 September 1911, Judge Carleton married for the second time, marrying Annie Josephine McKeen, the eldest daughter of Mr. and Mrs. Joseph McKeen.

J. L. Carleton was also an amateur playwright having written and performed in his own plays while living in Saint John. Carleton continued to write plays and in 1918, his play, "The Crimson Wing," won first prize in the Canadian play competition of that year. A number of his plays were published first by the Dramatic Publishing Company of Chicago and later by the Cornhill Publishing Company of Boston, Massachusetts.

On 5 February 1930, Judge Carleton was forced by ill health to resign as county court judge. After a lingering illness, he died in 1936, at Woodstock, New Brunswick, aged 74 years.