[treetalker]

For those interested, the executive order set forth the Obama administration's policy. The first Trump administration attempted to wind down DACA through an agency memorandum. In a splintered ruling that, among other things, wrestled with pertinent provisions of the Immigration and Nationality Act, the Supreme Court invalidated the Trump administration's agency action as arbitrary and capricious under the superseding principles of the Administrative Procedure Act.

https://www.supremecourt.gov/opinions/19pdf/18-587_5ifl.pdf

So Obama's executive order was not de facto law; rather, the Trump administration violated the law in the way it went about shifting policy. And as the Supreme Court noted, executive policies can be changed — but statutory law must be respected when doing so.