A trove of leaked documents has revealed the scope of the FBI's powers and ability to turn a blind eye on civil liberties of people they target as informants. A series of investigative reports published by The Intercept have brought to light the "secret rules" the US agency follows and its growing powers as an intelligence-gathering organisation.

A redacted version of a 2015 edition of the FBI's Confidential Human Source (CHS) Policy Guide, made available on the investigative news website, uncovers various methods used to recruit informants, both domestic and foreign.

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The CHS guide expands on the FBI's so-called Type 5 assessments that authorise agents to investigate people in the US, who are have not committed any crimes, but could be recruited as informants.

Called the "source identification package", it enables the FBI to procure derogatory information of a person and use it to coerce him/her into cooperating. However, the FBI claims this information is simply used to prevent it from being blindsided by an informant's vulnerabilities.

"This type of thing was done in the past, but it was never formal," retired FBI special agent Peter Ahearn told The Intercept.

A separate classified FBI document titled CHS Assessing states that the individual's personal information could be used as "a means to induce him/her into becoming a recruited [informant] mainly through identifying that person's motivations and vulnerabilities".

According to the guide, the FBI can "attempt to psychologically evaluate the target to determine the target's motivations, mental stability and loyalties and will seek information on the target's habits, hobbies, interests, vices, aspirations, emotional ties, and feelings concerning his country and his career and his employer".

Moreover, minors are also allowed to be recruited without the consent of their parents, if permission is given by an FBI special agent in charge.

One of the agency's most practised methods of recruiting informants of other nationalities is by approaching immigrants and using the "immigration relief dangle" – as carrot for citizenship – in order for them to cooperate. Agents are not allowed to make direct promises of citizenship or protection against deportation, but informants revealed that they were more or less assured such securities.

According to the guidelines, agents can only work with informants who have legal immigration status and need to assist illegal immigrants to obtain one before being recruited by the FBI. For this, the bureau makes arrangements with Immigration and Customs Enforcement (ICE).

However, in many cases, the agents offer "temporary immigration relief", but later help ICE locate and deport immigrants once they are of no use. "If the [informant]'s location is unknown, the [FBI agent] must work with ICE to locate the individual," the classified manual reads.

"In most cases, individuals will go to the FBI and the FBI will say, 'Yeah, we don't have any problem with you; you're cleared,' and yet ICE is aggressively going after them," Miami-based immigration lawyer Ira J Kurzban explained. "To the extent that this document reveals what's really going on, it's obvious that the FBI is working with ICE notwithstanding what they're telling the individuals."

Under the Significant Benefit Parole Program, the FBI can bring "inadmissible or deportable" informants into the country if they can assist in investigations and provide worthwhile information.

Similarly, the Deferred Action Program, permits an immigrant – typically not allowed to leave and reenter the country – to travel abroad on FBI operations.

Diala Shamas, a lecturer at Stanford Law School who represented individuals targeted for informant recruitment when she was working with the Creating Law Enforcement Accountability & Responsibility project, believes that this creates a "perverse incentive structure", in which informants are "incentivised" to be of value to the authorities.

"It will further incentivise them to create investigations when there wouldn't be one otherwise," she explained. "In the traditional criminal context, the law enforcement community is conscious of the risk that coercing informants increases the likelihood of getting bad intelligence. But in the counterterrorism and intelligence context, this caution has been thrown out the window."