Lembit Opik, a former Lib Dem spokesperson who served under Nick Clegg and Charles Kennedy, defended the peer's indiscretions, calling on the public to commend him for stepping down.
"He’s got to be respected for this. People need to lay off him now. He’s done exactly what people wanted him to do," Opik told The Spectator.
The ex-MP for Montgomeryshire claimed he knew of many Commons colleagues who had taken illicit drugs, including some at the very top tier of Government.
Lord Sewel was caught out in a front page exposé from The Sun
"If every member of the Commons, for example, who’s taken illegal substances had to resign – whether or not they were caught – there’d be a massive number of resignations straight away, even in the Cabinet," he said.
"What [Lord Sewel's] been accused of may be personal and embarrassing, but it’s not actually illegal."
His comments come days after Independent columnist Grace Dent also jumped to the defence of the peer, claiming that she thought many people were "quietly impressed the old boy still has it in him".
"Sewel laughs in the face of tepid Horlicks, squealing hearing aids and a mania about wheely bin collection times. No, he is a glorious worst-case scenario of “successful” twilight years.
"It is hard to know whether to be appalled or to applaud the two-fingers attitude to what the world expects “nearly 70” to look like."
Since the scandal surfaced on Monday, David Cameron has announced his intention to plough ahead with plans to flood the House of Lords with more peers.
The Prime Minister said he had no intention to revisit proposals to make the unelected Lords more democratic, and instead signalled that he would create more Tory peers this year and in coming years.