The law dictates who can be deported, generally not who must be deported.
Who must be deported is mostly left up to discretion.
And since deportation is very expensive and drastic - an option of last resort - it's usually better for all involved to come up with other arrangements.
Most prior presidents had good sense enough to understand that mass deportation is a major foot-gun, politically and economically. And kind of morally monstrous.
For better or worse, the arrangement that's been informally agreed upon is to let most of the undocumented who have been here a long time, remain (dreamers, etc).
Sadly, that left them all vulnerable to the discretion of a capricious criminal wanna-be dictator like Trump.
Who must be deported is mostly left up to discretion.
And since deportation is very expensive and drastic - an option of last resort - it's usually better for all involved to come up with other arrangements.
Most prior presidents had good sense enough to understand that mass deportation is a major foot-gun, politically and economically. And kind of morally monstrous.
For better or worse, the arrangement that's been informally agreed upon is to let most of the undocumented who have been here a long time, remain (dreamers, etc).
Sadly, that left them all vulnerable to the discretion of a capricious criminal wanna-be dictator like Trump.