The elections unit at Nicholson Graham & Jones has launched a hotline for returning officers who encounter legal problems in the run-up to the General Election.
It will deal with any query 24 hours a day, seven days a week, until the week after polling day.
A pager service will guarantee a return call within 1minutes.
This is the first General Election for the unit, which was set up three years ago and is run by two partners and two assistants.
The NGJ team also acts as adviser to the Liberal Democratic Party.
But the unit's head, partner Piers Coleman, said the helpline was designed to avoid election problems and should not throw up a conflict of interest.
He said recent decisions had increased the burdens on returning officers.
In one instance - the Hammersmith and Fulham case in 1994 - a proxy turned up to vote for a woman at a local election only to find that the vote had already been cast.
The candidate for whom the proxy intended to vote lost the election by one vote. It was ruled that the returning officer and his staff had been to blame.
Coleman said the unit itself had come about because the contracting out of local authority legal services had caused a gap in election law expertise.
The political parties use outside advisers on election issues. The Labour Party refers to the high-profile partner,
Gerald Shamash, from the London firm Steel & Shamash, while the Conservatives have been linked to the City firm Penningtons.
At he time of going to press, he Liberal Democrats were understood to be still in talks on whether to take legal action over the exclusion of the party from a pre-election television debate between the Tory and Labour leaders. Nicholson Graham & Jones declined to comment on what stage the talks had reached.