A judge cannot block an emergency
declaration. Congress can vote to end it,
but that would take a 2/3 majority in
both the house and Senate. And I believe
Trump can veto that vote if Congress
doesn’t pass legislation to fix the
emergency. Where the president can be
sued is from a landowner if the government
tries to seize his property thru eminent
domain as the landowner would have standing.
Sure there will be some problem areas such as recalcitrant landowners — just build around them and patrol for now.