An Astonishing, Frightening First for the Country

For months now, it has been apparent that Donald Trump might well become the first former president of the United States to be indicted. Now the once unthinkable has taken place. A grand jury in Manhattan has handed up an indictment of Donald Trump over his alleged coordination of hush-money payments in advance of the 2016 election. The indictment itself remains under seal.

It wasn’t supposed to happen this way. For one thing, it wasn’t supposed to happen today. Trump himself had announced earlier this month that he expected to be “arrested” on March 21; on the basis...