Among the tools the Trump administration is using to get states, local governments, nonprofits and schools to agree with its directives is the withholding of federal dollars. Although the government can use the power of the purse to accomplish many things, the courts have also drawn lines on the limits of its use. There are, in fact, unconstitutional conditions that can be attached to spending power.
The power of the purse — or the ability to appropriate money, as located in A...