The party is expected to establish a commission in the new year to examine possible answers to the so-called "West Lothian" question, which formed the intellectual basis of the most coherent attack on the devolution proposals of the Callaghan government.
The inquiry's remit will reflect the party leadership's determination to press ahead with plans for a Scottish Parliament, with tax-raising powers, early in a Labour administration.
But it will seek to establish whether an answer can be found to the question posed repeatedly in the late 1970s by Tam Dalyell, an anti-devolutionist, and the then MP for West Lothian - whether it was justified for Scottish MPs to vote on English and possibly Welsh legislation which no longer applied in Scotland, because it covered issues to be determined by the Scottish Parliament.
The commission is likely to be headed by a high-ranking Scottish Labour figure with UK-wide shadow responsibilities, like Donald Dewar, the Chief Whip, or Lord Irvine, whom Mr Blair will appoint as Lord Chancellor if he wins the election. It will almost certainly include other senior front- benchers, including George Robertson, the shadow Secretary of State for Scotland and Ann Taylor, the shadow Leader of the Commons.
The Labour leadership is open-minded on the outcome and Mr Blair has made it clear that he has no intention of backing down on the detailed commitment to a Scottish Parliament - already drawn up with the Liberal Democrats - whatever the conclusions.
But its existence raises the possibility for the first time that the present total of 72 Scottish MPs at Westminster - the large majority of whom are at present Labour - could be reduced to compensate for new powers which will be devolved under Scottish home rule.
So far, even though there are more Labour MPs per head of population in Scotland than in England, Labour has not suggested that the numbers should be reduced. But the Liberal Democrats are already committed to reducing the number of Scottish MPs at Westminster.
John Major is certain to press the arguments raised by the West Lothian question in the run-up to the general election, as he did in the 1992 campaign, when he warned that devolution meant that the "future status and number of Scotland's MPs at Westminster would inevitably be diminished".
The Tories are already preparing to question the potential role of Gordon Brown as Chancellor, sitting for a Scottish seat but fixing tax rates for England and Wales. Such tax rates might not be the final levels for Scotland - at least in theory - because of the Scottish Parliament's right to add or subtract up to 3p in the pound to or from UK tax rates.
The terms of reference of the Labour inquiry are likely to be wide-ranging and could include an examination of whether there is any case for allowing some business for England and Wales to be decided only by English and Welsh MPs. Although Labour is committed to setting up a Welsh assembly, this would have more limited powers than the Scottish Parliament and no right to levy taxes.
The inquiry is less likely to re-open the question of regional government in England as a possible answer to the West Lothian question. While Mr Blair is committed to a regional elected authority for London, the party has made it clear that it will only agree to regional assemblies elsewhere where there is clear public demand tested in a referendum.