Judge Alsup from the 9th Circuit wrote the first decision, and he specifically states that Trump has the authority to write a new policy.
I also suggest you browse through the Administrative Procedure Act.
The APA gives specific rules for overturning prior E.Os., and for writing new E.Os.
The APA also forbids federal judges from reviewing E.Os. that enforce the exact language of a statute.
Congress or some other plaintiff could go to court and claim that the statute - the Immigration and Nationality Act - is unconstitutional, but they cannot touch an E.O. written by Trump that seeks to enforce the exact language in the INA.
I repeat my original statement - Trump's E.O. was a political scam to extend DACA until the 2020 election.
If Trump is reelected in 2020, he will copy George W. Bush and offer Amnesty to non-criminal DACAs in exchange for bogus promises to build The Wall.
I thought DACA expired. Trump just didn’t renew.
I suggest you pay attention to all the leftist judges blatantly defying the law and ruling against Trump.
If he did it your way they would rule against him anyway and we would still be waiting for SCOTUS to overrule them.