Constructive eviction is when a rental becomes so unlivable that the tenant is effectively forced to move out, and the law treats the departure as if the landlord had evicted them on purpose. The tenant never gets a court order or a notice from you. The conditions do the evicting, and a court can later decide that you, by letting those conditions stand, did the legal equivalent of changing the locks.
The doctrine usually turns on a serious failure that you knew about and did not fix within a reasonable time: no heat in winter, raw sewage, no running water, a roof that lets the weather in. The tenant typically has to actually leave within a reasonable period, because someone who keeps living there and paying rent is signaling the place was livable after all.
In practice
Say a tenant rents a unit at $1,800 a month on a 12-month lease. In month 4 the furnace dies in January. The tenant reports it in writing on the 2nd, then again on the 9th and the 16th. You do nothing for three weeks. On the 23rd the tenant moves out and stops paying.
You sue for the remaining 8 months of rent: 8 × $1,800 = $14,400. The tenant raises constructive eviction as a defense. If a court agrees the unlivable cold, your knowledge of it, and your failure to act amounted to constructive eviction, the lease obligation can be treated as ended on the move-out date. Your $14,400 claim collapses, and the tenant may also recover moving costs or the gap between the old rent and a higher replacement rent. The repair you skipped, maybe a few hundred dollars, becomes a five-figure problem because the paper trail ran against you.
Why it matters to a small landlord
The defense lives or dies on documentation, and you control half of it. When a tenant reports a habitability problem, the dated record of when you learned of it and how fast you responded is the whole ballgame. A work order opened the same day, a vendor scheduled within 48 hours, and a note logging the call is the difference between a tenant who waited and a tenant who fled. Build the habit of timestamping every interaction, which I cover in how to document tenant interactions, and keep your maintenance turnaround tight, especially if you manage from another time zone and cannot drive over on short notice.
Constructive eviction is the flip side of the implied warranty of habitability: the warranty says the unit must be livable, and this doctrine is what happens when it is not. It also overlaps with quiet enjoyment, the tenant's right to use the home without serious interference. Note that none of this is the same as a formal unlawful detainer, the court process you file to remove a tenant who will not leave. What counts as “unlivable” and how long you get to fix it varies by jurisdiction, so read your state's statute before you rely on any of this.