evidence: Many protesters across the states have been pictured defying social distancing guidance without masks or face coverings. Online, the debate about mask effectiveness still plays out, with some claiming masks are not effective - or enforceable under US law. [...] On Monday, New York Governor Andrew Cuomo said it was "disrespectful" for people to refuse to wear a mask in public. "You can literally kill someone because you did not want to wear a mask. How cruel and irresponsible would that be?" [...] At the same time as the Centers for Disease Control (CDC) announced new guidance that Americans should cover their faces in public to curb Covid-19's spread, President Donald Trump said it was "voluntary" and he himself would not do so.