ARB-registered Gillian Beckingham was in charge of the air-conditioning unit at the Forum 28 Arts Centre in Barrow, when it sprayed deadly bacteria into the air in August 2002. The incident led to the death of seven swimmers.
At a trial this time last year, Beckingham was found not guilty of manslaughter, but received a guilty verdict over health and safety offences.
But now the architect has won the right to appeal this verdict at London's High Court. Her lawyers claimed that the prosecution had failed to prove that she was responsible for the system.
The incident in August 2002 was the worst ever outbreak of legionnaires' disease in Britain, killing six women and one man, and infecting nearly 200 other people.