Franken, an author and former comedian appearing on the popular Saturday Night Live television programme, "received the highest number of votes legally cast and is entitled … to receive the certificate of election as United States senator from the State of Minnesota", the court ruling said.

The two candidates had been engaged in a months-long legal fight over the validity of the November 4 election.

A series of recounts in the state gave Franken a victory of just 312 votes over Coleman, prompting the Republican to challenge the accuracy of the recount.

Tim Pawlenty, the Minnesota governor and a Republican, is now expected to formally grant the senate seat to Franken.