(CNN) Attorney General William Barr decided Tuesday that some asylum seekers who have established credible fear and are subject to deportation cannot be released on bond by immigration judges -- a major reversal from a prior ruling that could lead to immigrants being held indefinitely.

The decision means the Department of Homeland Security alone will have the discretion to decide whether to release immigrants who crossed the border illegally and later claimed asylum.

The ruling effectively blocks concerted efforts by immigration lawyers and immigrant rights advocates to push for bond hearings for detained asylum-seekers. The advocates argue that there's no reason for the United States to detain people who are seeking safety and have already cleared hurdles to prove they have a credible case.

While advocates argued that bonds set for detained asylum-seekers were often prohibitively high, a number of crowdfunding efforts in recent months had aimed to help immigrants get money to pay bonds and get out of detention.

Asylum seekers who presented themselves at legal ports of entry were already unable to be released on bond by immigration courts.

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