Over on The Volokh Conspiracy, Jeff Milyo has a great post on the cost filter of burdensome disclosure laws. He titles it "Unintended Consequences of Grassroots Lobbying Regulations" but given the declared goal of limiting speech by supporters of the House passed Disclose Act I would argue that diminished speech is an intended consequence of these laws.

The benefits and costs of mandatory disclosure for grassroots lobbying campaigns are not limited to the question how much does the public need to know about a speaker versus how important is the safe harbor of anonymity for some speakers.  The process of disclosure has its own costs, a point that is not well-appreciated by many. Consider that once classified as a lobbyist, an individual or group must not only register and pay a licensing fee, but must also submit periodic reports...For sophisticated professional advocacy groups, these requirements are likely just a nuisance, but for ordinary citizens they can be quite daunting.

...In an earlier report also published by the Institute for Justice, I conducted a “compliance experiment” in which I asked about 250 people to try their hand at completing some state disclosure forms for a political committee.  Subjects were presented with a simple scenario that included a few different transactions, such as an advertising expenditure, an anonymous contribution, and an in-kind donation. Subjects were given actual disclosure forms and instructions from California, Colorado or Missouri.  The result wasn’t pretty; bottom-line: participants were flummoxed by the task.  Despite being incentivized with monetary payments, not one could complete the disclosure forms correctly; most made multiple major errors, and several couldn’t even begin to follow the official instructions. When debriefed on the experience, several participants expressed frustration and incredulity that anyone would be expected to complete such forms just to participate in the political process.  Some even offered that they would never want to get involved in politics if it meant complying with such rules.

...Survey evidence gathered by Dick Carpenter suggests that in the abstract financial disclosure for political actors is popular; this is likely because very few citizens run for office or even make campaign contributions, so they imagine such rules applied only to other people.  But once framed as whether the respondents own name, address, and employer should be made public, support for disclosure laws falls dramatically; further, most respondents agree that mandatory disclosure would make them less likely to financially support political causes. The unintended consequences of complex and overbroad laws are therefore not just the possibility of abuse by regulatory authorities, but the deterrent effect that such regulations have for citizen engagement in politics.  Regulation of grassroots activism in the states stands in stark contrast to the basic principle affirmed in Citizens United v. Federal Election Commission:

 “The First Amendment does not permit laws that force speakers to retain a campaign finance attorney … or seek declaratory rulings before discussing the most salient political issues of our day. Prolix laws chill speech for the same reason that vague laws chill speech: People ‘of common intelligence must necessarily guess at [the law’s] meaning and differ as to its application.’”

Much more here, go read.