“white nationalists, counterprotestors, violently clash”
— CNN
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There should not be a comma between “counterprotestors” and “violently.”
The way it’s punctuated, it would appear that there is an apposition indicating that the white nationalists are one and the same group as the counterprotestors.
Grammar! it’s gone the way of the curtsey.
— Roger W. Smith
August 12, 2017