Kern, who took over as head of Austria's centrist coalition government in May, raised objections to the deal in August when it was all but complete, arguing that some of its elements could lead to watering down food, employment and other standards and give foreign companies leverage over governments.
The Thursday ruling paves the way for the German government to formally endorse CETA at a meeting by the European Union ministers next week. Belgium's federal government favors the pact, but needs the support of the country's regions and linguistic communities to give its formal approval.
Widely seen as a possible blueprint for TTIP, a bigger trade deal the European Union has been negotiating with the United States, CETA aims to eliminate tariffs on 98 percent of goods immediately.
The vote could mean Belgium cannot approve the CETA deal, as its regional parliaments are not unanimously in favour.
Canada's envoy for CETA, Pierre Pettigrew, is expected to meet Friday with Paul Magnette, minister-president of the Walloon region, a spokesman for Canada Trade Minister Chrystia Freeland said.
The EU trade ministers are scheduled to vote next Tuesday on whether to approve CETA.
Canadian Prime Minister Justin Trudeau said this week he was running out of patience after two years of delays and warned that killing the deal would send "a very clear message. that Europe is not productive".
Promoting the agreement, rapporteur Artis Pabriks said the deal "is important geopolitically as well as economically". As for Wallonia, the Globe and Mail quoted an European Union official as saying that the chief issue was that local politicians believed "CETA will be bad for their region, and that it was negotiated with big businesses in mind rather than the small- and medium-sized enterprises, or farmers, in the Walloon region".
Canada remains focused on having CETA signed this fall and provisionally enacted in early 2017, Lawrence said. While negotiators for Ceta replaced the proposed ISDS mechanism with a new Investment Court System, a joint letter by 101 law professors said this was still insufficient.
Mr. Valls said France will try to convince the Walloons that the deal is a good one for Canada and the EU.
All EU member states must individually ratify CETA before it can come into effect, but the vote in Wallonia now puts the whole process in doubt.
Senior European officials have told The Canadian Press that the obstacle thrown up by Wallonia is the single greatest remaining threat to CETA as it enters its final stages.
They are the 3.5 million inhabitants of a mainly French-speaking region that makes up much of the southern half of Belgium.