One of the more powerful and unusual tactics in litigation against the Trump Administration could become the “against type” amicus brief. Filing an amicus brief joined by Republicans critical of the Trump Administration and with some claim of expert knowledge made by these Republicans related to the constitutional issues can be a powerful tactic to use in courts. As an initial signal that this is correct, notice the role that amicus briefs questioning the national security rationale played in debates surrounding the opinions and even sometimes in the opinions themselves in the cases that worked their way through the Fourth and Ninth Circuits.
When a speaker expected to argue one side argues the opposite side, it can be an effective argument. The media will devote more attention to the argument. Consider, for instance, all of the attention paid to the argument made by former Republican Representative Bob Inglis, who led impeachment efforts against President Bill Clinton, that Trump has committed more problematic actions than Clinton. Citizens looking for “source cues” about what the Republican Party position is on this issue will not just be looking to the Trump Administration as guidance as to what to think about the issue being litigated. There is plenty of evidence that citizens use this mechanism to decide how to react to legal matters just like any other matter. If Justice Clarence Thomas argues something, for instance, the reaction will be different to his argument than it would be to the exact same argument made by Justice Ruth Bader Ginsburg simply because the argument was made by Justice Thomas. Judges who are particularly persuaded by lawyers with their same inclinations can be persuaded by seeing an amicus brief filed on behalf of a lawyer with whom they agreed in prior matters. Within the legal community, there are certainly many conservative lawyers and judges who were and remain very skeptical of Trump, and for that audience amicus briefs filed by conservatives against Trump could be powerful signals that there are conservative concerns based in the Constitution with the actions of the Trump Administration.
This suggests a litigation strategy for other organizations challenging actions by the Trump Administration: find Republicans who agree that the actions by the Trump Administration pose constitutional problems and have them sign on to legal efforts to challenge those actions. If it passes, find conservative federalists to agree to challenge problematic portions of the repeal of the Affordable Care and Patient Protection Act. Find conservative federalists devotees to agree to join challenges to the Trump Administration’s sanctuary city actions.