Irish Times view on Scottish independence: Impetus builds for a vote

If composition of parliament affirms support, another referendum should follow

With less than a month to go to the hard-fought Scottish Parliament election, First Minister Nicola Sturgeon appears to be leading her Scottish National Party (SNP) to a clear majority.

With or without the backing of former mentor Alex Salmond's new Alba party or the Greens, it seems likely a majority of members of the new parliament will endorse a call for another referendum on independence, one that UK prime minister Boris Johnson has vowed not to allow.

A majority in parliament will represent a clear expression of the Scottish will on a referendum – parties reflecting different positions on other issues will present themselves on both sides of the argument, so electors' choices are preserved. And although in 2014, as then prime minister David Cameron made clear in his memoirs, a referendum was unavoidable – "people had voted for it: we would deliver it" – Johnson's position is that there should not be a ballot on the issue for at least another generation. He cites the precedent of the 41-year gap between the two referendums on EU/EEC membership.

However, a refusal to accept the majority view would represent a constitutional Rubicon for the Union, former senior civil servant Prof Ciaran Martin argues in an important paper. The glue holding it together, he argues, since the resolution of the Irish question in 1921 has been consent, "the separate and collective consent of four constituent parts, each of which is free to withdraw''. A scenario where Westminster ruled Scotland instead through "the force of law'' only would profoundly change the relationship and undermine the legitimacy of its rule.

The hurdles faced by a Scottish majority determined on a constitutional road to independence are already high.The Scots are told that the choice whether to hold a vote or not – let alone whether to respect its result – must lie with Westminster. The Union as a whole must be allowed to decide on the right to secession of any of its parts or to dilute parliamentary sovereignty. No matter what sort of pro-referendum majority emerges in Edinburgh. And now they are told there will be no referendum.

Following the 2014 narrow defeat of independence, the British government unfortunately spurned the opportunity to set out any thresholds or frameworks for possible future referendums. Others, like Canada, have done so. And the Belfast Agreement provides that "at any time it appears likely" to a Northern Secretary that a majority of voters in Northern Ireland "would express a wish for a united Ireland" he/she is obliged to call a referendum. On the face of it, that threshold has been passed in Scotland where polls increasingly show independence majorities. If, as expected, that position is strongly reaffirmed in the elections, a referendum should follow.