A few things:

1. This is promissory estoppel for contracts. There are lots of types of estoppel, and not all are related at all to what this post is talking about.

2. This post misses a super important requirement for the examples it gives, which is that you have to detrimentally rely on the promise. Put another way - you have to have been injured (monetarily) by the promise to recover.

Usually this means you did something in response to the promise that cost money and can't be undone easily.

Being upset at pizza type would not cut it :)

3. The house example is wrong for another reason - promises/contracts to buy/sell houses must be in writing and signed to be enforceable (at least in the US). This is known as the statute of frauds. If i promise you verbally to sell you a house, and later do not, it will generally not be enforced.

(You may be able to recover something for detrimental reliance, but you will not be able to force me to sell you the house based on a verbal promise)

Most states also apply this to certain other types of purchases/etc.

Interesting! I'm curious, are there examples of the non-promissory estoppel that could give me an idea of what those look like?

There are lots

Judicial estoppel - Being barred taking positions directly the opposite of ones you've taken in litigation before (and benefited from). IE you can't say "we didn't do it" in a civil lawsuit, and then say "we did do it" in a bankruptcy proceeding.

Estoppel by deed - In real estate, f i give you a deed to a house, i can't later turn around and claim it wasn't a valid deed.

Prosecution history estoppel - in patents, if i disclaim something in a proceeding with the PTO to get a patent, i can't later claim infringement for the thing i disclaimed.

IE if the USPTO gives me a prior art reference and says it overlaps, I can say "my patent doesn't cover that" and disclaim rights to the part they think overlaps. I can't later sue someone over that overlap.

This was super helpful and easier to understand than the wiki page. Thanks for taking the time to writing these!

Sure.

One thing to keep in mind is that there are lots of nuances being lost in what i write - they are just generalizations

Lawyer here. Long life story short -- it wasn't until well after law school and mostly not practicing for many years that I learned to love the law, and it is for simple ideas like this, that we would do well to reconsider. I know, especially in tech, people tend to think "We should pass new laws because of this thing," and frequently I'm thinking, "No, we should just go back to X."

Relatedly -- if we could just inject the term "bailment" into all of our discussions about data and privacy we could really get somewhere.

Equity is a fascinating and complex/weird body of law, and estoppel is a great introduction to it. For anyone interested in learning more, a good starting point is learning about the maxims of equity and their applications in real property.

I can't decide if this is an educational blog post or veiled legal threat.

Kind of seems like the later.

Edit 2: According to the child comment this was just a TIL blog post. Thanks for the clarity.

Original comment:

I was prepared for a story time about a legal issue Ente is facing, and since they don’t mention one I now have more questions than I started with.

Are they the recipient of an estoppel order? In the process of issuing them? Are there implications we should hear about but don’t? Or is this all just for fun, like “it was lunch and learn legalese day” at HQ?

I’m not familiar with this company, but seeing as how they provide E2E encrypted photo backups at a time where law enforcement is globally maneuvering to end such things has me wondering if maybe something more happening. Which saddens me since I’m now interested in the product…

Edit 1: rereading this comment I feel like it’s a bit cynical, so i removed some speculative remarks. Strange topic to get your product mentioned on the HN front page, but I suppose it worked!

I'm probably extrapolating a lot from very little, but here's my take:

> It was legal day today at ente

I took this to mean that they regularly meet with their legal team, not for a specific purpose, but just to touch base and catch up on anything that may useful to have council's eyes review (read: informal meeting with legal team). Estoppel could have come up any number of ways, talking about contracts and their enforcement, someone asked a question that naturally veered into that territory, etc.

It sounds like they're involved in something legal that concerns estoppel.

Someone promised or mentioned something that someone acted upon, and now it has changed.

Nothing like that! This is just a genuine TIL post :)

Author here. We were reviewing our legal docs today. It was just a word that I found interesting. I wrote about it. That was all.

How would you prove it? In most countries an oral agreement is equivalent to a true contract but it's hard to prove.

It's hard for the plaintiff to prove, but it's also hard to for the defendant to disprove without committing perjury. Keep in mind that in a civil lawsuit, the case is decided on balance of probabilities and there is no assumption in favour of either side. Also, there is no right to silence.

What I take from this is that if you want to rent your house to someone and don't want to sell it and certainly don't want the renter to lie about it and say you promised to sell the house, you then have to specify in the renting contract that there will be no selling of the house to that renter. This greatly lowers the probability that you then changed your mind and somehow promised orally to sell it.

Sort of like bait-and-switch.