Experts believe a court battle is unlikely and that the issue will be solved in negotiations. The LAT points out that "openly defying a subpoena has little precedent." If subpoenas are issued and the White House aides refuse to cooperate, Congress could vote to find them in contempt. But making things just a tad weirder, the Justice Department would normally be in charge of prosecuting this kind of case. Congress could also use other tools at its disposal, such as withholding funds from an agency or refusing to approve any nominees.Perhaps the "experts" are correct. But using precedent for such a showdown is a mistake. Bush is not like previous Presidents ... even Nixon.
The NYT points out that even if an interview isn't under oath, lying to Congress could still be a crime. But the WP notes aides would not face "the same level of criminal charges" if they're not under oath.
I'm a very lucky person with every allergy known to man but still happy to be enjoying a wonderful life living in the best place in the world!