Mistakes and irregularities have been commonplace in the deportations of many immigrants and there have been "systematic violations" of the basic rights of immigrants, a report presented Thursday revealed.

The study entitled "Deportation Without Due Process," put together by professors of Stanford Law School and Western State University College of Law and attorneys with the National Immigration Law Center, analyzes thousands of documents obtained under a Freedom of Information Act lawsuit.

"This report synthesizes information obtained from never-before-released U.S. government documents and data," said Jennifer Lee Koh, assistant professor of law at Western State University and the report's lead author.

She said that during the past 10 years, via the stipulated removal program authorities deported more than 160,000 people "without ever giving them their day in court."

The report emphasized that 96 percent of the people who signed documents agreeing to voluntary deportation never received the advice of a lawyer before doing so.

"These people had no idea that it was a deportation order that they were signing," argued Karen Tumlin, a lawyer for NILC and co-author of the report.

She also emphasized that many of the immigrants - the great majority of them Hispanics - did not understand English and could not pay for a lawyer, and thus signing the order violated their basic rights and, in reality, was not voluntary.

In addition, the investigation found that a script used by immigration agents "is written in broken Spanish, replete with condescending and misleading phrases."

Jayashri Srikantiah, professor of law and director of the Immigrants' Rights Clinic at Stanford Law School and another coauthor of the report, said that it is necessary to remedy the situation by following the recommendations contained within the study.

"First of all, Immigration and Customs Enforcement should not allow the alternative 'deportation or jail' to continue being presented to people, especially to those people who do not have legal representation," Srikantiah said.

Also, the Executive Office for Immigration Review should require that judges hold a hearing in person with the immigrants who do not have an attorney before they sign the voluntary deportation order.

"ICE should be prohibited from using stipulated removal on vulnerable noncitizens and those with strong ties to the U.S. These include, at a minimum, children, people with mental disabilities, and lawful permanent residents," the report urges.

According to ICE statistics, in fiscal year 2010, U.S. authorities deported more than 392,000 immigrants, of whom about 195,000 had no previous criminal records.