Should MPs forfeit their seat when they change party?

To answer this question, two principles of ­parliamentary government must be examined.

The first is the “representative principle”. Traditionally, this has prevailed, not only in the United Kingdom but across other Commonwealth jurisdictions. It was set out in 1774 by ­Edmund Burke, who asserted in his address to the electors of Bristol: “Your ­representative owes you, not his industry only, but his ­judgment; and he betrays you instead of serving you if he sacrifices it to your opinion.”

In other words, a parliamentarian, as a ­representative, is not bound by their ­constituents or their party, but only by their conscience. A parliamentarian is chosen primarily on account of their personal merits, and only ­secondarily on the basis of a party manifesto or policy ­commitments.

Once in Parliament, representatives should use their own personal judgement to decide how best to serve the public interest, for which they are responsible at the next General ­Election. Members of Parliament are therefore well ­within their rights to change party if they think it is in the public interest to do so.

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The representative principle does not give ­parliamentarians carte blanche to act as they will; only to act as they think best. That is a ­crucial distinction. To change parties, as an act of self-sacrifice because they believe it to be necessary in the public interest is acceptable; to do it for peevish, personal motives is not.

This traditional representative view has been challenged, generally by those on the left, who have held to a more delegatory principle of ­parliamentarianism. According to the delegatory principle, a parliamentarian is not supposed to rely upon their own judgement but to carry out the will of those who have elected them.

On ­major policy decisions, they are bound by their party’s manifesto commitments. On ­minor ­matters, there might be some flexibility, but ­discretion is still expected to be exercised within the general principles of their party, and under the direction of party leaders.

If we adhere to the delegative principle, to leave one party and join another undermines the one thing they were sent to Parliament to do – to represent the opinions and policy priorities of their voters. It is a betrayal of the people.

The delegative principle makes the ­democratic part of parliamentary democracy possible. It ­enables voters to choose between ­manifestos and policy programmes and thereby gives ­people a degree of control over the direction of public affairs. If we adhered only to the representative principle, each parliamentarian would be chosen as an individual free to exercise their own judgment; voters would have no ability to give them a mandate to pursue particular ­objectives.

Some, adhering to this delegative principle, have argued for a rule that MPs or MSPs who quit their party and join another should lose their seats. This rule has been introduced in some Westminster-derived constitutions. The Constitution of Bangladesh (Art 70), at one ­extreme, causes MPs to lose their seat if they leave their party, or even vote against their party in Parliament.

We should be cautious, however, about ­embracing such provisions. The ­representative principle cannot be so lightly discarded. It makes the parliamentary part of parliamentary democracy possible. It enables MPs or MSPs to vote with their conscience, to resist party whips, to take a stand against their own ­leadership. It allowed Robin Cook and Clare Short to vote against the Iraq War.

If we adhered only to the delegative principle, there would be no real point in having ­parliamentarians at all; every vote would be a foregone conclusion.

There is a danger that causing MPs or MSPs to lose their seats if they change party would ­further enhance the already excessive power of party leaders and party managers (whips), ­making it harder for backbench ­parliamentarians to stand up on matters of principle.

The strongest disciplinary measure a party can currently impose is to withdraw the whip and deselect at the next election. That is already a strong enough incentive to toe the line. If we want parliament to function as a ­representative assembly that can hold the Government to ­account, party discipline does not need to be made any stronger.

In particular, a parliamentarian should never be at risk of losing their seat merely for rebelling against the party line, nor for having the whip withdrawn, where there is no voluntary and ­deliberate act of changing party.

Perhaps it should come down to the ­conscience of the parliamentarian, given the particular circumstances. To move from SNP to Tory is different from moving from SNP to Alba. Should Lisa Cameron forfeit her seat? No. Should she resign it? Probably.