Both the IRS and Americans United say the agency in recent years has increased the number of investigations it conducts on organization suspected of abusing their tax-exempt status and the speed with which it recommends action.
In 2006, the IRS received 237 complaints and selected 100 groups — 44 churches and 56 nonchurches — for examination. More than half of those cases remain under investigation, according to IRS statistics.
"However, the IRS did substantiate improper political activity in 26 cases and issued written advisories. So far, there are no revocation recommendations," according to an agency report on the statistics.
In 2004, the IRS selected 110 cases for examination and revoked the tax-exempt status of five organizations. Of those five organizations, none were churches.
The last church to have its tax-exempt status revoked was the Church at Pierce Creek near Binghamton, N.Y., in 1992.
The Church took out an ad in 1992 that read: "The Bible warns us to not follow another man in his sin, nor help him promote sin — lest God chasten us … How then can we vote for Bill Clinton?"
That ad, like a speech from the pulpit, is a violation of section 501(c)(3) of the tax code, according to the IRS.
"Generally, the law passed in 1954 prohibits any tax-exempt organization from participating on behalf or in opposition to any candidate," said IRS spokesperson Nancy Mathis.
Legally, Mathis said, candidates are allowed to speak at churches, much like Sen. Barack Obama, D- Ill., did over the weekend in Chicago when he delivered a sermon about fatherhood. Churches who host candidates, however, are supposed to invite the opposition candidate as well.
In 2007, the IRS investigated and dropped charges against United Church of Christ following a conference in which Obama was allegedly endorsed during an introduction. Obama formerly belonged to Trinity Church, a member of United Church of Christ, but split with the church following controversial comments by his old pastor Rev. Jeremiah Wright.
"There is a very simple test religious leaders can use to determine if they're violating the law," said Rev. Barry Lynn, executive director of Americans United for the Separation of Church and State. "Ask yourself: 'Is what I'm doing intended to help someone's candidacy?' If the answer is 'yes,' don't do it."
"Tax exemption is not a right; it's a privilege that comes with certain restrictions," Lynn said.
According to Lynn, Booth's "free speech" argument is specious because taxpayers should not have to subsidize pastors' political activities they do not agree with.
Booth is not the only pastor challenging the IRS this year.
The Alliance Defense Fund, a Christian advocacy group based in Scottsdale, Ariz., is enlisting ministers around the country to endorse candidates from their churches' pulpits on Sept. 28.
"Pastors on that day will evaluate candidates in light of scripture," said Erik Stanley, senior legal counsel for the group. "Our hope is that the IRS will initiate investigations and we can bring this into the federal courts."
Churches, he said, are doubly protected by the First Amendment to make political speeches, because it protects both free speech and freedom of religion.