A Supreme Court judge has blasted former NSW Labor MP Eddie Obeid and his sons for bringing an "unreasonable" and "irresponsible" lawsuit against the corruption watchdog and ordered the family to pay a multimillion-dollar legal bill.

In a scathing judgment delivered on Monday, Justice David Hammerschlag said there was "every reason why" Obeid and his sons Moses, Paul and Eddie jnr should pay the costs of every person sued in the case.

From left, lawyer Nick di Girolamo, Moses Obeid, Eddie Obeid jnr, lawyer Tim Breene (back) and Paul Obeid at the Supreme Court last year. Credit:Peter Rae

This included former Independent Commission Against Corruption chief David Ipp, QC, against whom the Obeids had made baseless allegations of misconduct that Justice Hammerschlag described as "of the gravest kind".

Legal sources said the bill would easily exceed $2 million, on top of the Obeids' own costs.