“One company specialising in mobile forensics is telling investigators not to even look at phones with Face ID, because they might accidentally trigger this mechanism. “iPhone X: don’t look at the screen, or else… The same thing will occur as happened on Apple’s event,” the slide, from forensics company Elcomsoft, reads. Motherboard obtained the presentation from a non-Elcomsoft source, and the company subsequently confirmed its veracity.”
Source : Cops Told ‘Don’t Look’ at New iPhones to Avoid Face ID Lock-Out – Motherboard