(CNN)An appeals court hearing Tuesday on former President Donald Trump's claim to keep January 6 documents from his presidency private showed that Trump faces an uphill battle to keep the documents out of the hands of House investigators... ...The case touches on some unsettled law around whether a former president can litigate executive privilege claims when the incumbent sides with transparency. And the three judges on the appellate panel -- all Democratic appointees -- signaled that they found some of the case's questions difficult, even as they expressed doubt about Trump's claims.... ...They also challenged the lawyers with several hypothetical...