Most people would rather not kick up a fuss - but if a neighbour blocks your light with an unsightly extension, or if a car mechanic sets up in business next door, chances are you will be sorry you didn't do something about it. It is easier for the proverbial camel to pass through the eye of a needle than for a planning application to avoid public notice. People looking for planning permission must publish their intentions in approved newspapers (the planning authority has a list) and the application has to be with the authority within two weeks of the publication.

A notice must be posted in a prominent position on the site and this must stay in place for at least one month. The sign has to be A4 size and give specific details of the proposed development.

Utilities planning to install overhead transmission or distribution lines for electricity and telecommunications are excluded from the requirement to post a notice. To make sure nothing "slips through" despite these precautions, most interest groups receive a weekly list of planning applications by post from local authorities. This costs an annual fee of around £180, although in most cases residents' associations pay a reduced fee for the service. You don't have to actually live in an area to object to a planned development. Anyone is entitled to write to their local planning office and make a comment or objection on an issue they feel strongly about.

Another popular myth is that it costs money to lodge an objection. There is no charge for making an observation for or against a planning application at the initial planning stage. Once the decision has been made, an appeal to An Bord Pleanala will cost an objector to the development £120. For the applicant appealing to An Bord Pleanala against the planner's refusal to grant permission however, the cost is £300.

Most of the estimated 15,000 letters which arrive each year on the desk of Dublin Corporation planning administrator, John Wade, are about the loss of an amenity. This can be a national issue such as the erection of phone masts or pylons, or simply a neighbour's new wall blocking the light.

"It's very important to state in your letter why you're objecting, because planners have to take everything into consideration," says Mr Wade. "What gets up most people's noses is not being consulted by neighbours about what they intend doing. It will certainly raise hackles if you don't."

Seems straightforward. Yet emotions tend to run high where hearth and home or even a view are under threat. While no-one has an absolute right to a view, Dublin Corporation say they deal sensitively where a resident is threatened with losing their view because of a planned roof extension or new housing development.

Three residents of a south Co Dublin suburb lodged an objection with Dun Laoghaire and Rathdown County Council when a neighbour built an extension higher than the planning permission allowed and with an unauthorised chimney. This was eventually successful and the neighbour was ordered to comply with what was approved.

However, a final appeal by the owner for retention of a window that should have been blocked up ended in partial victory for the developer.

Some rogue developers operate on the basis that local corporations are sometimes reluctant to enforce the demolition of a house or extension once it is in situ. Dublin Corporation has an Enforcement Section whose job it is to have unlawful developments pulled down, but according to one spokesperson "retention is the way it normally goes".

Because the planning process operates on an open basis, applicants for planning permission are entitled to know who is objecting and why. Objections submitted in writing are entered into the file, which is available for all interested parties to read.

This invariably causes friction and world war three occasionally breaks out between neighbours. One Rathmines mews owner found herself in the firing line when she objected to an unauthorised child-minding business operating in a neighbour's newly built extension. Several court appearances and £800 in legal fees later, the case was dismissed on the basis that there was no proof "beyond doubt" that the neighbours accepted money for the child-minding service.

Enlisting the help of a resident's association is one way to minimise expense and any backlash from frustrated applicants. Persuading a community group to take up the cudgel on your behalf can cause an objection to gather momentum, especially if there is an environmental element involved. In recent months, Dun Laoghaire and Rathdown County Council have received submissions from community groups on behalf of residents objecting to a proposed travellers' halting site for Dalkey Quarry. Since local councillors have signalled their unwillingness to vote in favour of the proposal, it is unlikely to go ahead in the foreseeable future, according to an authority spokesman. "If you put a halting site on the moon, someone would object," he says.

Local interest groups are now lobbying for special amenity status for Killiney Hill and Dalkey Quarry, similar to that already conferred on the Hill of Howth. If planning is refused and the application goes to appeal, objectors can ask for an oral hearing. This is usually granted by An Bord Pleanala if there is considerable public concern about a planning application. It costs £60 on top of the £120 fee to object at appeal stage and anyone can attend, although only those who registered the objection will be allowed to speak. Appeals to An Bord Pleanala must be in writing, and complete - that is, nothing can be added to the submission at a later date. As with objections at the initial planning stage, the full grounds for the appeal with supporting material and arguments should be included.

Even if the planning authorities allow the development to go ahead, having taken all objections and observations into consideration, it's not the end of the road. Objectors still have a right of judicial review within two months of the board's decision.

The court is not permitted to reopen the planning merits of the case and will only look into whether the appeal board's decision is invalid. This can prove very costly if the case goes against you. "Residents' associations aren't busy-bodies, they don't object to everything," says Renee Lawless of the Leinster Road Residents' Association. She finds that local applicants for planning approval now discuss their proposal with the association before sending off the application.

Information leaflets outlining how to lodge an objection to a planning proposal are available from most council offices. However, according to Renee Lawless, what is needed is a comprehensive guide book on planning laws that can be easily understood. In the meantime, anyone anxious to bone up on the subject can apply to join one of the courses on planning law held periodically at Trinity College, Dublin.