What is Adverse possessions or possessory possession?
Adverse possession is when a person gains title to a property if they have remained in that same property for a certain amount of time.
A person or persons who has occupied the Land for the prescribed amount of time, in certain circumstances can prevent the true owner from reclaiming the Land.
Length of time required to claim title 
In order for a person to successfully claim title to a property over the true owner, and extinguishing their title at the same token, a person must gain uninterrupted possession of a property for 12 years or longer in Queensland and New South Wales.
In Victoria for a person to be successful in their claim of adverse possession, they must have stayed at the one place for 15 years or more.
A person in New South Wales can potentially make a claim for Crown land through adverse possession if they have lived in the same place for 30 years.
How is adverse possessions proved?
The claimant must have evidence of occupation and possession.
Adverse possession means not a mere occupation but also actual physical possession in an open and peaceful manner, without consent of the original owner.
The claimant will need to be able to prove to the Titles Office in the State of jurisdiction that they have occupied the land for the entire period of time required.
If there is any form of permission (such as a license, lease, or agreement to use the land), adverse possession cannot be claimed because it will be clear that the owner never intended to pass over ownership.
Who can claim adverse possession?
Anyone who is prepared to take possession of a vacant property or land subject to meeting all the requirements of the Laws of the State of jurisdiction.
If you were intending to attempt this seek advice from a property Lawyer as gaining adverse possession isn't an easy process and few people will gain land through this method.
The law and squatters
Under the Limitations Act 1969 in NSW, a claim of adverse possession can be made against an owner after living in the property unobstructed for a period of 12 years.
This is an interesting law also known as "squatter's rights".
Squatters are not tenants.
Squatters occupy premises without the consent of the person who is legally in possession (typically the owner).
That's why property owners want them occupied by legal tenants as a property that has been unoccupied for some time has the potential to be claimed by a squatter.
This could happen in the case of a deceased estate that may be in litigation for some years because of claims against the Will or no Will existing and the relatives do not have the right to take possession and have to leave the property empty until the estate is resolved
Garth Brown's Comments
Adverse Possession was recently bought to the fore when a Sydney squatter made news because he is attempting to claim legal ownership of a million-dollar terrace by citing a historic tenancy law using an arcane real estate law.
Whether or not this squatter will be successful remains to be seen but it highlights the dilemma faced by property owners with unoccupied premises (as outlined in the above paragraph), as squatting has become a way of life for a growing number of people and it can be very difficult and expensive evicting them.
