24. In such action the owner is entitled to a judgment

Unless the parties to a lease agree otherwise, either may transfer his interest. A tenant will be able to assign or sublease his right to occupy the property, and the landlord has a right to sell his reversion on the property. A tenant assigns a lease when he (the «assignor») transfers his entire interest in the property, meaning all of his rights and duties under the lease, to another party (the «assignee») for the entire length of time remaining on the lease. The principal significance of an assignment is that a new landlord-tenant relationship is established between the landlord and the assignee. The landlord and the assignee are now in privity of estate with one another, and the assignee will obtain the benefits and bear the burdens of all covenants running with the land.

By contrast, a sublease is a transfer of anything less than the tenant's entire interest to a third party (the «sublessee»). In other words, a sublease is created when the tenant leases the property to another party for any period of time that is shorter than the remaining time on the lease. A sublease does NOT establish privity of estate or contract between the sublessee and lessor. The sublessee is not liable to the landlord while the original lessee is still liable to the landlord under privity of contract and privity of estate.

A is correct. This question requires you to distinguish between an assignment and a sublease. When the tenant and owner entered into a written lease of Blackacre for a term of three years, the tenant became liable for the monthly rent for that entire three-year period, under both privity of contract and privity of estate. When, after living there for one year, the tenant leased Blackacre to the friend for just one year, this was a transfer of less than the tenant's entire interest in the property, amounting to a sublease. As a result, the friend was never in privity with the owner because he was only a sublessee. The owner may recover all of the $24,000 in lost rent money from the tenant individually but is not entitled to any judgment against the friend.

B is incorrect. The owner is not entitled to even a reduced amount from the friend, despite the fact that the friend lived in Blackacre for six months without paying rent. The friend was a sublessee of the tenant, not an assignee, so the friend was never under privity with the owner. It was the tenant who maintained liability for the rent under his original contract with the owner. When the friend abandoned the property and the tenant subsequently lived there, also without paying rent, the 24 months of total unpaid rent was exclusively the tenant's responsibility.

C is incorrect. As explained above, any attempt to divide the rent owed to the owner would be a misapplication of the rules governing subleases. The fact that the tenant subleased Blackacre to the friend prevented the friend from ever entering into privity with the owner. The tenant remained in both privity of contract and estate with the owner and is liable for the entire amount.

D is incorrect. This answer would be correct if the friend had been an assignee and therefore liable for unpaid rent AND if this was a jurisdiction that had adopted joint and several liability. But without privity of contract or privity of estate between the friend and the owner, joint and several liability cannot apply.