I'm flying domestic-overnight-international and I attempted to get into UC (waiting for upgrade smh) on the first day. I had flown similar itineraries and was allowed access at LAX UC/Polaris and LAS UC before. After denials at ATL and C club at ORD, an amazing agent at one of the B clubs who initially disagreed with me dug through the policies and eventually found the exceptions. The policy says along the lines of the following:
If a checked-in boarding pass is printed that includes a lounge access-eligible, downline flight that departs on the next day after midnight, admit them.
This language can be found on internal "Web (rights?) tips", "Access by customer type", "Exceptions" in the footnotes.
The initial scan of the outbound BP
will be denied and agents have to manually process access by noting the downline flight and confirmation number.
So it's not that "same-day" means within 24-hour of international departure but it's whether an eligible boarding pass can be printed.
As long as you hold an eligible BP, you can be admitted to UC/PL under this exception, even if your international segment departs on the next day after midnight.
The agent graciously called C club and said she would pass this info to other ORD clubs so hopefully people won't run into issues at ORD anymore!