The civil war within the body representing Scotland's councils has taken an altogether more pressing turn with the news it could cost "rebel" councils more than £3.5 million in existing payments to leave.

The Convention of Scottish Local Authorities (Cosla) is not a body in its own right, but made up of the member councils, so each is responsible for a share of its operating costs, including staff and buildings, its chief executive Rory Mair argued to council leaders yesterday. It means the eight Labour-run councils seeking to leave have an ongoing legal liability, even if they quit the body, for the joint costs, he said.

Should the councils, including Glasgow, Aberdeen, South Lanarkshire and Inverclyde, follow through on their intention to leave a body they feel is no longer serving its purpose, they will incur a bill between them of £3,552,000, Mr Mair explained.

Councils facing this bill dispute this will be legally enforceable, but it was obviously a convincing enough fear for North Lanarkshire, which cited the costs as one of its reasons for declining to join the rebels this week. If North Lanarkshire knew the price, why didn't the others?

Cosla says the £3.5m figure is a minimum, based on estimates of the kind of one-off "settlement" fee that leaving might incur - with each council's share determined broadly by its size. But more sabre-rattling yesterday suggested the costs could rise far higher if some councils seek to contest this situation legally.

Yet that raises fresh questions - who would a council be suing? As Cosla only exists as a confederation of councils, the departing councils would be in the ludicrous situation of pursuing a case in which the defendants include themselves.

Whatever the course, if the eight councils which have given notice that they will leave do so - and the rift now looks irreparable - the losers will be council tax payers. Yet most ordinary people have a limited understanding of what Cosla does and will struggle to understand why they should continue to pay for a body which their own council has left.

Scotland needs strong local government. Many feel it is a democratic tier which has become increasingly attenuated, seen by Scottish ministers as little more than a vehicle for delivering policy. It should be much more, providing local accountability and genuine responsiveness to regional needs.

That doesn't mean Cosla shouldn't change. Variation in the needs of those in different geographies has always made it hard to reach agreed national positions. It may be that different groupings, such as a coalition of the larger metropolitan councils, would be useful. Ironically, the rebellion comes at a time when the organisation, under president David O'Neill, was reviewing its purpose and role in strengthening local government.

Cosla's role may need reviewing. But at a time when most taxpayers are struggling with domestic costs, food banks are on the rise and pressure on services is intense, public patience for a protracted and extremely costly internal battle is likely to be in very short supply.