The Corporations Act 2001, Section 115 provides:

A person must not participate in the formation of a partnership or association that:

                     (a)  has as an object gain for itself or for any of its members; and

                     (b)  has more than 20 members;

unless the partnership or association is incorporated or formed under an Australian law.

There are some exceptions.

A breach of that section is an offence of strict liability.