FAST said it will consider using powers under the Copyright Design and Patent Act 1988, rather than taking civil action.
Directors of firms found guilty under the CDPA could face a maximum of 10 years in prison and unlimited fines. About one in four UK firms use unlicensed software, according to the Business Software Alliance.
John Lovelock, head of legal affairs at FAST, said it had last used the CDPA in 1999. The change in tactics was in response to rising levels of software piracy among UK businesses, he added.
"If we have one or two high-profile cases going to court and we get results, we think this will be enough to get people to sit up and take notice," said Lovelock
Sian Croxson, a partner at law firm DLA, advised IT directors to make sure their company has an up-to-date software audit.