I must admit, I haven't fully studied the relevant Acts that outline the investigative powers and procedures that ASADA are bound, or the Act that creates the body's existence, however I have had a bit of experience with the rules regarding evidence and procedure regarding criminal matters.
Evidence that is inadmissible can still be admitted if it is considered to be significant enough. All relevant factors are considered so it can become quite obscure.
Considering the nature of an ASADA investigation, which I would presume is not as rigorous and rigid as a criminal one, it may be quite possible that even if the investigation is deemed 'illegal', the evidence obtained may be still admissible.
I of course don't intend to question your previous experience / knowledge, however, having sat in on the Federal Court case today, and having heard Justice Middleton raise this precise matter, I heavily doubt that any such information gathered unlawfully will be allowed to stand if and when the investigation thus far is deemed unlawful. It was in fact suggested that ASADA would have to restart their investigation without use of previously gathered information.