Legal Question in Criminal Law in Australia

Even though you and your mates broke into an abandoned lot with no sign-age and a fence that was down, you might still be charged with "trespass". What concerns me is that the lot was still surrounded with some fence, and as such; it's boundaries were recognisable.

Further, the fact that you write that you "broke into" the abandoned lot, also suggests to me that its boundaries were clearly recognisable.

Section 3(b) of the INCLOSED LANDS PROTECTION ACT 1901 defines enclosed lands as:

any land, either public or private, inclosed or surrounded by any fence, wall or other erection, or partly by a fence, wall or other erection and partly by a canal or by some natural feature such as a river or cliff by which its boundaries may be known or recognised, including the whole or part of any building or structure and any land occupied or used in connection with the whole or part of any building or structure.

However, It may be that the "abandoned lot" was genuinely abandoned i.e. that there is no owner or person apparently in charge of those lands. If this were the case then by my reading of Section 4 of the INCLOSED LANDS PROTECTION ACT 1901 you would not be guilty of the offence.

Section 4 of the INCLOSED LANDS PROTECTION ACT 1901 provides as follows:

(1) Any person who, without lawful excuse (proof of which lies on the person), enters into inclosed lands without the consent of the owner, occupier or person apparently in charge of those lands, or who remains on those lands after being requested by the owner, occupier or person apparently in charge of those lands to leave those lands, is liable to a penalty not exceeding:

Moreover, even if there were an owner of the land you may have a defence of honest and reasonable mistake, on the basis that you genuinely believed the land was abandoned. The difficulty with this would be that although there is no sign, the presence of a fence could make your belief that there was no owner an unreasonable one.