Nine peers have been cleared by House of Lords authorities over allegations made regarding their expenses claims.
Most involved a £174 overnight allowance for peers whose main homes were outside London but were accused of rarely visiting their "main" homes.
But Lords authorities accepted that each had spent enough time there to qualify for the allowance.
Meanwhile Labour peer Lord Clarke will be investigated by Lords authorities over his expenses.
His claims have also been investigated by the Metropolitan Police who on Friday said there was "insufficient evidence to provide a realistic prospect of conviction".
On Tuesday Clerk of the Parliaments Michael Pownall said he had referred Lord Clarke's case to the Lords sub-committee on lords' interests and regarded it as "complex and serious".
The peers cleared by the Lords authorities are: Baroness Barker, Lord Colwyn, Lord Hayworth, Baroness Hayman, Baroness Morgan of Drefelin, Lord Morris of Manchester, Baroness Northover, Baroness Thornton and Baroness Whitaker.
Most of the cases involved the use of the £174-a-night allowance to enable peers whose main homes are not in London to stay near Parliament.
It followed stories in the Sunday Times suggesting that peers had designated little-used properties outside London as their "main" home in order to claim the overnight allowance.
In his letter, Mr Pownall notes that he is there to check claims were made in accordance with the rules - not "retrospectively to devise rules for the current scheme which have not been in place to date".
He said there was no clear definition about what constituted a main home in the current scheme - so he had asked a Lords committee which rules on peers' allowance to come up with some "essential criteria".
It had decided that a minimum threshold for visits to a property designated as a "main" home for expenses purposes should be "at least once a month" when Parliament is sitting. Time spent there during recess was "also a relevant factor".
Some peers were accused of designating properties owned by relatives - including their mothers - as their main home.
But Mr Pownall, the most senior administrator in the House of Lords, said that was "appropriate" in some cases where peers had a connection to the property and paid towards its running costs. "Main" homes could also be rented in some circumstances, he said.
He also dismissed complaints against former Lib Dem chief executive Lord Rennard and attorney general Baroness Scotland.
He said allegations that Lord Rennard had claimed for overnight stays on days he was not at Parliament were not "well founded", arguing that just because the peer had not spoken or voted on those dates did not mean he was not there.
"These statistics do not necessarily reflect the wider contribution which a member makes to the work of the House," he said.
He also dismissed suggestions Lord Rennard had mis-designated his "main" home.
In Baroness Scotland's case, Mr Pownall said he had not considered the complaint because she was a minister "throughout the period for which we hold records and so not entitled to claim" under the reimbursement scheme.
Under reforms proposed by the independent Senior Salaries Review Body the old allowances system for peers would be replaced.
It favours a £200-a-day attendance allowance for peers, who are not salaried, but says they should have to prove they have been at Parliament.
The plans were criticised by some peers who agreed to back the reforms in principle, but not the detail in a vote in December.