US fencing one-two on another night of frustration for the French
Kiefer, who was the first American to win an Olympic foil gold when she triumphed three years ago in Tokyo, retained the title with a comfortable 15-6 victory over her younger teammate Scruggs in the final at the stunning Grand Palais venue.
"It's insane," said Kiefer. "These three years have been so short and so long at the same time. Every day it's been a freaking battle and I have so many people to thank for helping me get here on this day, in this moment.
"It's absolutely historical," she added. "Lauren fenced amazing this whole season and she deserves all this respect."
Scruggs stunned Italian favourite Arianna Errigo in the quarter-finals to reach the Olympic final at the first attempt.
"I'm super happy, you know," said a tearful Scruggs, the first Black American fencer to win an Olympic medal in a women's individual event.
"Of course you always want to win but I still got a medal."
Later, France failed to deliver a gold medal for the second day in a row, with Yannick Borel losing painfully 15-9 to Kano.
Borel's defeat was reminiscent of Hong Kong's Vivian Kong victory against France's Auriane Mallo-Breton in the women's epee event on Saturday.
Despite a partisan crowd at the Grand Palais cheering him on, Borel lost the first two touches and never managed to recover.
"Yannick is very strong," said Kano, a team gold medallist in Tokyo in 2021. "I can win, I won - I'm very happy."
Mohamed Elsayed of Egypt was awarded epee bronze after a tough bout with Hungary's Tibor Andrasfi, winning 8-7 in the last second of sudden-death.
It was an all North American podium in the women's foil event, with Canada's Eleanor Harvey winning bronze.
"I feel like I'm in a dream," Harvey told reporters.