Civil defamation laws could equally be used to undermine freedom of the press. In any case, the 'can of worms' you are talking about was the state of affairs in the UK until 2009 and is currently the case in several US states and yet somehow we still have people in those states openly criticizing a sitting president.

Rather than throwing our hands in the air, maybe we could expect our governments to craft laws in such a way that we can punish people for willful lies resulting in death while still preserving our right to free speech and the press.