[spokeshave]

If he was able to persuade Loretta Lynch

Then what happens when Lynch reads about it in the newspapers...?

Can she decide to "uncertify" the sanctuary cities...?

Thanks in advance.

[Degaston]

Any effort by her to try to “undo” the certification would have to be done by notice/publication. In there she would have to explain its rationale using reasonable legal justifications, or else she/others involved would have culpability for malfeasance. So its unlikely that she would attempt to do so now.