Illegally obtained evidence can be admitted to court if it is decided that it’s more important that it be admitted than not. For example if I illegally record you admitting to being a serial killer, this is likely to be admitted since murdering lots of people is a much more serious crime than illegal recording. See 138 Discretion to exclude improperly or illegally obtained evidence in www.legislation.gov.au/C2004A04858/latest/text