The ACLU said schools and groups that want to invite Ramadan and others into the United States are concerned about the ideological exclusion provision.
According to the ACLU documents, the State Department's Foreign Affairs Manual says the provision is directed at those who have voiced "irresponsible expressions of opinion."
The organization said it violates the First Amendment and has, since 2001, resulted in the exclusion of scholars, human rights activists, and writers, barred "not for legitimate security reasons but rather because the government disfavors their politics."
The ACLU said some scholars and writers are reluctant to accept invitations to the United States because they will be subjected to scrutiny and may be denied entry.
Rebekah Carmichael, a spokeswoman for government lawyers, said she had no comment Friday.
In the case of Ramadan, a native of Switzerland, the ACLU said he was excluded last year for making donations that totaled $1,336 to the Association de Secours Palestinien , an organization the US government said he should have known provided funds to Hamas.
Ramadan said in court papers the donation was for humanitarian aid and he would not have given it "if I had thought my money would be used for terrorism or any other illegal purpose."
Before his visa was revoked in 2004, Ramadan had spoken at Harvard University, Stanford University, and elsewhere.
