The Scottish voluntary sector is made up of 45,000 organisations, of which half are registered charities.

This large and dynamic part of the economy represents some of the most vulnerable people in society and often serves as their voice in public debate. That voice has not been heard enough in the debate on Scottish independence so far.

The Scottish Council for Voluntary Organisations (SCVO) is concerned that guidance issued by the Office of the Scottish Charity Regulator (OSCR) last month, while designed to clarify the rules of engagement for charities, will actually dissuade them from entering the independence debate. The concerns are justified. Charities must ensure that their own constitution does not prohibit campaigning, and any campaigning furthers the charity's purposes and does not promote a political party. What stance charity trustees take beyond that is a matter for them, not the regulator.

On the key question of whether charities may campaign for a Yes or No vote, OSCR needs to be clearer in its guidance. It states: "Supporting a particular outcome is not necessarily advancing a political party, something which is clearly not allowed by charity law." It later states: "It seems unlikely to OSCR that supporting or opposing the prospect of Scottish independence as a whole can be easily linked to the furtherance of charitable purposes," and continues, "the charity trustees should not adopt a position or campaign on the 'bigger' question as this might lead the charity into inappropriate political activity." Trustees would require a divining rod to fathom that.

If trustees conclude that either independence or remaining in the Union best fits with furthering the charity's purposes, they may feel duty bound to campaign for that outcome. OSCR's guidance does not state clearly whether it would be legal for them to do so or not.

No-one would argue that there are pitfalls for charities in entering this debate in too cavalier or strident a manner, least of all charity trustees.

Take the example of a member of the public who spends her free time fundraising for a health charity. Imagine she is a supporter of independence. How would she react if she found her favourite charity started campaigning for the Union? What about the environmental activist and pro-Union supporter who finds a charity he helps to fund is campaigning for independence? It is easy to see how voluntary organisations could and almost certainly would lose money and support as a result of taking an overtly political stance. Martin Sime, SCVO's own chief executive, has already provided a taster of the kind of controversy that can flare up around a charity if its bosses take a stance that is seen as being politically partial. Last year, he was accused of cosying up to the SNP leadership by voicing his support for a devo max option on the referendum ballot paper, something Alex Salmond was known to support but which was opposed by the pro-Union parties.

Some charities might feel constrained by fears about alienating key funders in local or central government. An organisation which relies for its survival in the munificence of the Scottish Government might not feel comfortable voicing doubts about the wisdom of independence.

So there are risks. Knowing this, many charities are likely to restrict their comments to how they perceive a particular constitutional outcome could affect their area of work; that is a perfectly honourable choice. If they wish to risk taking a broader stance, and can do so within the law, then it is their right to do so.