A man, who allegedly bashed an elderly Perth woman after posing as a police officer, was one of 154 immigration detainees released after the high court ruled against indefinite detention.

National affairs editor, Andrew Probyn, says the government has talked a big game over their new regime of preventative detention.

“This … appears to be non-existent, because it hasn’t been applied yet,” he told Tom Elliott.

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The detainee was on bail at the time of the alleged assault.

Image: Nine News.