Arthur Ellis studied at Osgoode Hall, was called to the Ontario bar in 1913 and set up practice in Ottawa.

He was rumoured to be in line to become Provincial Treasurer but was consigned to the backbench when Joseph Monteith defied pundits by retaining his seat in the legislature in the 1929 election.

After the Ontario Liberal Party under Mitchell Hepburn took power in the 1934 provincial election Ellis moved to the Opposition bench where he achieved prominence as finance critic.

[3] On November 25, 1935, he struck and killed a pedestrian on Highway 15 north of Kingston, Ontario and was charged with criminal negligence.

He was acquitted in 1936, but the notoriety of the incident hurt his chances as a candidate in the Ontario Conservative leadership convention, held several weeks after the trial, in which he placed seventh with ten votes.