Sue Ridgepipe I wonder if you are referring to the case of McLennan v Surveillance Australia.
That case is not going to prevent bonding. The point in that case was that the employer and the employee were operating under an Australian Workplace Agreement (an AWA) (and an Award, as it happens) which did not cover the bonding arrangement that they agreed to separately and later.
The bond agreement was agreed between the employer and employee outside and separately to the AWA. If it had been included in the original AWA, or as a variation to the AWA, by submitting it to the Employment Advocate and it being accepted, then it would have been enforced. As it was, it didn't bind the employee legally, primarily because it was not a part of the AWA. Consequently she was able to walk away without paying anything.
The lesson is that varing the terms and conditions of employment of employees who are already parties to an AWA (or a certified agreement) may not be binding if the agreements are not varied in accordance with the law.
This is a simplified explanation to suit this situation. If anyone wants to read the case, you'll find it
here