Estoppel

Once again my post points to Wikipedia, this time for the definition of estoppel.

I was particularly interested in equitable estoppel and I was confused by the statement "equitable estoppel can only be used as a defence". I kept thinking "Defence only, how does that help me?" Finally, someone much smarter than me pointed me to a simple example that I could understand. I was truly impressed with the beauty of the logic. The example:

Sue rents an apartment from Joe and her lease states the rent is due on the 1st of every month. After Sue moves in, she talks to Joe and Joe tells her it's OK if she pays on the 10th of each month instead of the 1st. Sue pays on the 10th for several months and one day she gets an eviction notice from Joe. He says that the lease states the rent is due on the 1st and that Sue has violated the lease by paying on the 10th. An eviction hearing is scheduled. How does the judge rule?

In Sue's favor! Sue asserts equitable estoppel as a defense to Joe's legal claim that Sue has violated the lease. Joe made Sue a promise that she relied on and Joe can't "harm" Sue by changing his mind even though the lease still states rent is due on the 1st, i.e. he is estopped from asserting his rights under the lease.

The example is, of course, a hypothetical.

I'll take the liberty of extracting (the full letter is posted) the Subject of a letter I received: "FMLA Notification".

I leave anyone bored enough to actually read my post with two simple questions to ponder; was a promise made and was I harmed when, and if, that promise was broken?