Electoral law is highly complex and urgently needs codification and simplification, as the Law Commission have rightly identified. In essence, every poll is run to a set of, what are called by election practitioners, 'conduct rules' specific to that poll. The conduct rules set out what the Returning Officer (RO) must do, and a timetable that they must adhere to in running a poll. There is no discretion to depart from the conduct rules. But when it goes wrong, subject to certain limits, the law throws the unfortunate RO a lifeline.
According to Section 46 of the Electoral Registration Act 2006, a returning officer for a parliamentary, local government or European election can remedy an act or omission by them or a 'relevant person' that is not in accordance with the rules of the election. This may be on his/her part, or on the part of a 'relevant person'. The only limit on what steps the RO may take is that they may not recount the votes given at the election once the result has been counted.
There are similar provisions for other polls.
As well as applying to ROs and their staff, a 'relevant person' (and their staff) covers the electoral registration officer, a presiding officer, a person providing goods or services to the returning officer (e.g. a printer of election documents), a deputy of these persons, a person appointed to assist or in the course of his employment assisting such a person in connection with any function he has in relation to the election.
Interestingly, this provision does not apply to the candidate or agent. Therefore an error in the nomination cannot be fixed under this provision.
Where an RO for a parliamentary or local government election may be guilty of an act or omission in breach of his official duty but remedies that act or omission by taking steps under section 46, s/he shall not be guilty of an offence. Using Section 46 therefore may well prevent the act or omission for being an issue which results in a challenge to the conduct of the poll.
It is nevertheless worth noting that if the election was conducted substantially in accordance with the rules, and the act or omission did not affect the result then a challenge against the RO will probably fail (Section 23 RPA 1983 for parliamentary elections and Section 48 for local elections).
This provision has never been tested in the courts, and so the extent that one can use it is untested. There are many examples of those who, to correct a very minor and ultimately insignificant breach have committed a much worse breach unwittingly by stepping outside the conduct rules. So use it, but with caution, and care.