Lawyers for the three elderly Kenyans - Wambugu Wa Nyingi, Paulo Muoka Nzili and Jane Muthoni Mara - hailed it as an "historic" judgment.
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The broadcast figure-turned activist died on Monday at her Los Angeles home from metastatic breast cancer, her family said.
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Melissa Mead has been campaigning to raise awareness of sepsis after losing her one-year-old son William to the illness.