[2] Settling in Calgary, he would begin to practice law with future MLA Alexander McGillivray, and was named King's Counsel on 19 March 1913.

[2] Tweedie was first elected to the Legislative Assembly of Alberta in a 1911 by-election and served the Calgary seat that had been previously vacated by Richard Bennett.

[citation needed] Thomas was appointed as a judge to the Supreme Court of Alberta Trial Division in Calgary on 15 September 1921[2] and subsequently resigned his seat in the House of Commons.

[2] Tweedie's reputation as a popular and well respected legal mind would be somewhat tarnished after his involvement assisting the Alberta Minister of Public Works Oran McPherson with his divorce in 1932.

Tweedie would hold court in the judge's library in Edmonton to expedite the process, and when McPherson's wife challenged the divorce, the matter ended up in front of the Privy Council.