David Yerushalmi is founder of the think tank Society of Americans for National Existence, which has drafted anti-Sharia model legislation, and listed as general counsel for many Islamophobic individuals and organizations.  The Anti-Defamation Leagus says Yerushalmi has a "record of anti-Muslim, anti-immigrant and anti-black bigotry."  Yerushalmi acts as an attorney for Frank Gaffney and Pamela Geller.
Anti-Sharia Model Legislation
Yerushalmi has authored the anti-Sharia model legislation introduced in more than a dozen states. 
According to the Center for American Progress:
"Yerushalmi’s obsession with Sharia law dates back to 2007 when his organization, the Society of Americans for National Existence, created the “Mapping Shari’a in America: Knowing the Enemy” campaign to determine what type of Sharia was practiced in every single mosque and advocated by Muslim American religious institutions. The director of this campaign was David Gaubatz, who would later co-author the Center for Security Policy-funded conspiracy book Muslim Mafia: Inside the Secret Underworld That’s Conspiring to Islamize America.
The press release for the Mapping Sharia campaign stated the initiative would “test the proposition that Shari’a amounts to a criminal conspiracy to overthrow the U.S. government.”
But the conclusion was never in doubt, for that same year Yerushalmi proposed legislation to make “adherence to Sharia” a felony punishable by 20 years in prison, falsely claiming that “Islam requires all Muslims to actively and passively support the replacement of America’s constitutional republic with a political system based upon Shari’a.”
Also that same year, Yerushalmi began developing the template for the current antiSharia legislation movement American Laws for American Courts at the behest of the American Public Policy Alliance, a right-wing-funded nonprofit advocacy group that claims “one of the greatest threats to American values and liberties today” comes from “foreign laws and foreign legal doctrines,” including “Islamic Shari’ah law,” which APPA claims is “infiltrating our court system.”
He soon was working with other members of the Islamophobia network to introduce this legislation across the country. The American Bar Association recognized the sweep of Yerushalmi’s “anti-Shariah initiative,” noting that “many of the legislators sponsoring the anti-Shariah initiatives in other states are using model legislation drafted by the American Public Policy Alliance.” . . . many of the bills were drafted with identical language to Yerushalmi's model legislation.
“Shari’a and Violence in American Mosques”
In June, 2011 Yerushalmi released “Shari’a and Violence in American Mosques,” which claims that more than 80 percent of U.S. mosques feature texts that promote or support violence. The report was published in June 2011 by Middle East Forum Quarterly, which is published by Daniel Pipes’ think tank Middle East Forum.
Almost immediately, Center for Security Policy's Frank Gaffney endorsed and promoted the report’s findings in his Washington Times column, claiming, “This paper describes an ominous jihadist footprint being put into place across the nation.” He referred to the report as proof that American mosques are “jihad incubators.” 
The Center for American Progress responds:
"In fact, a two-year study on American Muslims titled “Anti-Terror Lessons of Muslim-Americans” by academics David Schanzer and Charles Kurzman, with Duke’s Sanford School of Public Policy and the University of North Carolina respectively, concluded that contemporary mosques are actually a deterrent to the spread of militant Islam and terrorism.
Moreover, this claim has been categorically rejected by actual law enforcement experts and counterterrorism officials, too, including FBI Director Robert Mueller, U.S. Attorney General Eric Holder, and National Counterterrorism Center Director Michael Leiter, who testified at a February 9 hearing before the House Homeland Security Committee, saying, “Many of our tips to uncover active terrorist plots in the United States have come from the Muslim community.""
General Counsel for Islamophobic Groups
Center for Security Policy
Stop Islamization of America
Yerushalmi is also general counsel for Pam Geller's and Robert Spencer's Stop Islamization of America group, which the Anti-Defamation League has called an "anti-Muslim group" that "promotes a conspiratorial anti-Muslim agenda under the guise of fighting radical Islam." 
Stop the Madrassa
He is general counsel for the organization that attacked a New York City secular charter school as a religious Madrassa and Islamic front, the group Stop the Madrassa: A Community Coalition. The school, Khalil Gibran International Academy, taught the Arabic language and culture as part of its international curriculum. Islamophobe Daniel Pipes, who supported the "Stop the Madrassa" effort, later told the New York Times that using the word "madrassa" which could mean either a secular or a religious Islamic school in Arabic, was "a bit of a stretch." 
Right-Wing Christian Groups
Yerushalmi has worked with the Thomas More Law Center, a non profit public interest law firm “dedicated to the defense and promotion of the religious freedom of Christians” in a number of cases.
He and Thomas More represented Pam Geller's Freedom Defense Initiative in several lawsuits to allow her group to post ads on buses for the RefugeFromIslam.com website asking people to leave Islam. 
Yerushalmi and Thomas More also filed a suit against the federal government claiming its loan to American International Group, Inc., as part of the bailout of the global insurance giant amid the 2008 financial crisis, was illegal since the company had financial products that allegedly promoted Islam and were anti-Christian.
He also worked with Thomas More in a case defending the notorious Koran-burning Pastor Terry Jones. 
Yerushalmi received $274,883 from CSP for consulting services. His organization the Society of Americans for National Existence reported $385,586 in revenue in 2007, $389,841 in 2008, and $310,479 in 2009, according to the organization’s latest tax filings. 
- Wajahat Ali, Eli Clifton, Matthew Duss, Lee Fang, Scott Keyes, and Faiz Shakir, "Fear, Inc.: The Roots of the Islamophobia Network in America, Center for American Progress, August 2011.
- “David Yerushalmi: a Driving Force Behind anti-sharia efforts in the u.s.,” anti-Defamation league, march 25, 2011.
- Eli Clifton, The Roots of the Islamophobia Network (audio), Antiwar.com, 30 August 2011. (19:10 min mark)
- Tim Murphy, “meet the white supremacist leading the gop’s antisharia crusade,” Mother Jones, March 1, 2011.
- Frank Gaffney, Jr., “gaffney: united shariah of america,” The Washington Times, June 7, 2011.
- “Extremism: Backgrounder: stop islamization of america (sioa),” anti-Defamation league, march 25, 2011.
- Elliot, Andrea, "Critics Cost Muslim Educator Her Dream School", The New York Times, April 27, 2008.
- Thomas More Law Center, "Yerushalmi" keyword search, accessed September 1, 2011.