(Photo: AP/Bill Clark/CQ Roll Call) Democracy Spring protesters on Capitol Hill on April 13 demonstrate against big money in politics. rules-logo-109.jpeg T he biggest problem with the campaign-finance system is also the hardest to correct: the escalating millions spent on politics behind a veil of secrecy. On its face, this should be an easy problem to fix. Why not simply require donor disclosure for all campaign activities? The hard part is that many groups that claim to be engaging in advocacy or public education are actually making political expenditures. The courts have ruled that advocacy groups have a right to keep their donors private, lest the government tread on constitutionally protected free speech. But that means that disclosure rules must be carefully crafted to protect both voters’ right to know who is paying for American elections, and organizers’ rights to petition the government without harassment or intrusion. Right now, the regulatory regime tilts heavily in favor...