The 3-0 victory in a best of five looks more conclusive on paper than it was on the water as Law had to wriggle out of two penalty situations in their first race.
He then controlled the second but won the third by only inches. In the other semi-final, sailed in rather shifty winds alongside Hurst Castle in the western Solent, Denmark's Morten Henriksen also won 3-0 against Peter Holmberg, the US Virgin Islands America's Cup skipper.
They were swapping the lead in their first race and Henriksen had again to come from behind to take the second. But, in the third, a distracted Holmberg let Henriksen slip while claiming he had been fouled, and it was all over.
"Today showed how my crew - Andy Hemmings, Jules Salter and James Stagg - can perform under pressure," Law said. "We have been trying to get to this stage for a year and it all came down to talent, teamwork and the will to win. Bertrand was also going to be tough. He sails with real Gallic flair and passion."
In the play-off for the minor places, Thierry Peponnet (France) was fifth, Murray Jones (New Zealand) sixth, Magnus Holmberg (Sweden) seventh and Andy Green (Great Britain) eighth. The top four places will be decided in two best-of-five series today.
All 14 yachts on leg five of the BT Challenge from Cape Town to Boston are now approching the most tactically demanding section as they work out how to cross the Doldrums most efficiently. The winner of three of the legs so far, Mike Golding's Group 4 is again leading.Reuse content