Cash for laws is worse than cash for questions. In 1994 John Major was vilified for presiding over a culture of sleaze when two insignificant Tory MPs were found to have accepted money to ask questions in Parliament. Four Labour peers have now been accused of being willing to accept cash to alter legislation.

Parliamentary questions seek to influence policy through the front door. The peers, by contrast, are being accused of seeking to influence legislation not through the front door by putting down amendments, but through the back door by nobbling ministerial chums. They are alleged to have breached the Lords code of conduct, which declares that “Members of the House... must never accept any financial inducement... for exercising parliamentary influence”, and “must not... promote any matter in return for payment”. The four strenuously deny the allegations, which are to be considered by the sub-committee on Lords' Interests. But, unlike the Commons, the Lords has no sanctions against wrongdoers.

In 2000 the Neill Committee on Standards in Public Life suggested that the Lords did not need sanctions since they enjoyed “a culture rooted in the concept of personal honour”. The Lords, unlike the Commons, has no power to expel or suspend members, even if, as with Lord Archer of Weston-Super-Mare, they have a criminal conviction.

A peer can be deprived of his or her writ of summons, the entitlement to a “seat, place and voice” in the Lords, only by an Act of Parliament. But this has not happened since 1919 when two peers were so deprived for supporting “the King's enemies” during the war.

Peers do not receive a salary, but are paid allowances. It is difficult, therefore, although not impossible, to impose financial sanctions on recalcitrants. There is a power to fine, but it was last exercised more than 200 years ago. This means that the only sanction is naming and shaming a peer.

Lord Woolf, the former Lord Chief Justice, has said that “there is great difficulty in finding a suitable way of combining the traditions of this House with the conventional and contemporary approach to dealing with complaints of this sort”. What he means is that peers, following the lead given by Lord Neill of Bladen, have allowed themselves to believe that their House is still a repository of the Great and the Good.

That, indeed, is what the House of Lords seemed to be in the years immediately after the Life Peerages Act of 1958. Early life peers such as Lord Franks and Lord Robbins were quintessential members of the Establishment, members of numerous royal commissions and committees, and men as little likely to abuse their position for financial gain as to swear in church.

Today, by contrast, many of the working peers, including the four accused of wrongdoing, are former politicians, the sort of people who might well be in the Lords were it to be elected. If, like MPs, peers come to be professional politicians there is no reason why sanctions for non-compliance with parliamentary standards should be any different in the two chambers.

Until 1999 it might have been argued that sanctions were not needed in the Lords for another reason, namely that the House enjoyed so little influence over legislation. About two thirds of its members were hereditary peers, and the Tories enjoyed a permanent majority. Precisely because the peers appreciated that their position was difficult to defend from the point of view of democratic legitimacy, they tended not to interfere with government legislation.

But the House of Lords Act of 1999 removed almost all of the hereditary peers, and since then no single party has enjoyed a majority in the Upper House. The House has become more active. Indeed, there is a much better chance of amending legislation in the Lords than in the Commons. In the Commons, a government can generally rely on the whips. In the Lords, it has to win the argument.

In 1995, after the cash for questions scandal, the Commons established the office of an independent Commissioner for Standards to investigate complaints. On receiving his report, the Commons can impose penalties, which might include withholding an MP's salary for a specified period, suspension, including loss of pay or, in the very last resort, expulsion. Last year, for example, Derek Conway, the Conservative MP for Old Bexley and Sidcup, was suspended from the Commons for ten days after a report by the commissioner. Only three MPs have been expelled this century. They include Horatio Bottomley, convicted of fraud in 1922. When visited in prison, amid his mailbags, he was asked: “Sewing?” “No,” he replied, “Reaping.” More frequently, the offending MP is allowed to resign, as with John Stonehouse in 1976, when he was convicted for theft, forgery and fraud.

The 1999 Act has made the Lords an effective legislative and scrutinising chamber. It must now regain public trust. It should establish its own independent Lords commissioner for standards, and give itself the power to fine and to suspend recalcitrant peers. The culture celebrated by Lord Neill has become as irrelevant to modern times as the annual Gentlemen v Players cricket match at Lord's.

Vernon Bogdanor is Professor of Government at Oxford University. His book The New British Constitution will be published by Allen Lane this year

Times Recommends

• Fantasy world fuelled by sex, drink and drugs
• In short, the story is growing on us again
• A literary feast that I can’t wolf down