Freedom of expression is one of the most cherished of American liberties, but according to a report released Tuesday, many writers in the United States worry that the freedom to write critically about the government or concerning controversial subjects is threatened by the extent of domestic spying.

Literary organization PEN American Center conducted a survey in October of over 520 American writers in order to determine if their research methods and writing styles were influenced by recent news concerning the extent of domestic surveillance of social media, email and phone records.

The survey found that 73 percent of respondents were deeply concerned about privacy rights and freedom of the press. 1 in 6 participants in the survey reported that they have begun avoiding writing or speaking about topics they fear may lead to their being subjected to surveillance, while another 1 in 6 were seriously considering doing so.

Many participants indicated that they had assumed they were already under surveillance, causing them to be reluctant to pursue research about certain subjects or communicate with sources or friends abroad for fear of endangering their counterparts.

The report from PEN quotes (but does not name) several respondents who expressed concerns.

“As a writer and journalist who deals with the Middle East and the Iraq War in particular, I suspect I am being monitored. As a writer who has exposed sexual violence in the military, and who speaks widely on the subject, likewise.”

“I have felt that even to comment on the Snowden case in an email would flag my email as worthy of being looked at.”

“I would hesitate to express in writing understanding for anti-American sentiments abroad, as I suspect that expressing such understanding might make me suspect in the eyes of the American security apparatus.”

“I have dropped stories in the past and avoided research on the company telephone due to concerns over wiretapping or eavesdropping.”

“I guess what’s most pertinent is that when I was writing my book … which deals with a lot of difficult material, I hesitated to research anything that could be related to child abuse/pornography (hesitate to even write that now).”

“I feel that increased government surveillance has had a chilling effect on my research, most of which I do on the Internet. This includes research on issues such as the drug wars and mass incarceration, which people don’t think about as much as they think about foreign terrorism, but is just as pertinent.”

The authors of the report list several recommendations they feel will would help restore public confidence in the privacy of communications and the protection of free speech, including ceasing what they call the “dragnet monitoring” of communications of U.S. citizens pending the restoration of Constitutionally required due process protections and disclosure of the full scope of domestic surveillance programs and what data has been gathered on citizens without a warrant. They also call for additional research into the relationship between government surveillance and intellectual and creative freedom.

PEN America is best known in the U.S. for its defense of author Salman Rushdie after the publication of his controversial novel The Satanic Verses.