Advocate Lutheran General Hospital, Park Ridge, Ill., part of Advocate Health Care.

U.S. District Court Judge Jorge Alonso has explained in a new court filing why he  switched from siding with two large Chicago suburban health systems that wanted to merge to favoring antitrust regulators that have fought the proposed merger.

The reversal, announced March 7 , stopped  the proposed marriage between Advocate Health Care of Downers Grove, the largest hospital network in Illinois, and Evanston-based NorthShore University HealthSystem. Such a merger  would have created the nation’s 11th largest nonprofit hospital system.

Basically, Judge  Alonso’s decision was that if he let the systems merge, it might have been harder to break them up later and “recreate pre-merger competition.”

Read Judge Alonso’s decision here.

Read  a Modern Healthcare article on this here.