Congress claims the power to compel testimony in an impeachment investigation. The Trump Maladministration frivolously claims total immunity to investigation of any kind. Judge Jackson, an Obama appointee, gets to make the first ruling on this. How much will that matter? Who will accept her opinion and come forward?
Don McGahn was among the first to get a subpoena from the House Committees gathering evidence on Donald Trump, and among the first ordered not to comply, way back in April 2019. So it is natural that he will be the first to receive a ruling.
Other such cases are following along behind, and will run all through 2020. Eventually we want decisions and the resulting testimony and documents