In the current case, there is no action by Congress. Since the House acting alone cannot change the law, the House lacks the standing to appear in court and speak as if it has the authority of the entire Congress for its position. Therefore, the President may legally reallocate funds and build the wall -- and Nancy Pelosi and the House Democrats leave with nothing.
For all the talk of the controversy as being between the President and Congress, it is really only between the House and the President, with the GOP controlled Senate on the President's side.
Excellent summation.
Perhaps House lawyers who yammer BS should be beaten with baseball bats till they shut their lying yaps.