I read that a thumbs-up emoji considered as legally binding agreement in Canada. Is a thumbs-up emoji considered as legally binding agreement in the United States?
If state-specific, I am mostly interested in California and Washington state.
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The judgment you have read about is South West Terminal Ltd. v Achter Land, 2023 SKKB 116. The judge did not hold that "👍" is categorically considered to be binding agreement. The judge applied the modern approach to contractual interpretation outlined by the Supreme Court of Canada in Sattva Capital Corp. v. Creston Moly Corp., 2014 SCC 53 and Ethiopian Orthodox Tewahedo Church of Canada St. Mary Cathedral v. Aga, 2021 SCC 22. This requires judges to interpret the text of the contract and indicators of acceptance in light of the surrounding circumstances.
Regarding interpretation, see Sattva:
a decision-maker must read the contract as a whole, giving the words used their ordinary and grammatical meaning, consistent with the surrounding circumstances known to the parties at the time of formation of the contract. Consideration of the surrounding circumstances recognizes that ascertaining contractual intention can be difficult when looking at words on their own, because words alone do not have an immutable or absolute meaning
Regarding formation, see Aga (internal citations removed):
 For present purposes, it will suffice to focus on the requirement of intention to create legal relations. As G. H. L. Fridman explains, “the test of agreement for legal purposes is whether parties have indicated to the outside world, in the form of the objective reasonable bystander, their intention to contract and the terms of such contract”. This requirement can be understood as an aspect of valid offer and acceptance, in the sense that a valid offer and acceptance must objectively manifest an intention to be legally bound.
 The test for an intention to create legal relations is objective. The question is not what the parties subjectively had in mind but whether their conduct was such that a reasonable person would conclude that they intended to be bound. In answering this question, courts are not limited to the four corners of the purported agreement, but may consider the surrounding circumstances.
See also Owners, Strata Plan LMS 3905 v. Crystal Square Parking Corp., 2020 SCC 29, para. 37:
the offer, acceptance, consideration and terms may be inferred from the parties’ conduct and from the surrounding circumstances
The conclusion about the 👍 emoji was case-specific. See paras. 62-63:
 ... Again, based on the facts in this case – the texting of a contract and then the seeking and receipt of approval was consistent with the previous process between SWT and Achter to enter into grain contracts.
 This court readily acknowledges that a 👍 emoji is a non-traditional means to “sign” a document but nevertheless under these circumstances this was a valid way to convey the two purposes of a “signature” – to identify the signator (Chris using his unique cell phone number) and as I have found above – to convey Achter’s acceptance of the flax contract.
1."Even if you supply a jurisdiction tag, we expect and encourage answers dealing with other jurisdictions – while it might not answer your question directly, your question will be here for others who may be from those jurisdictions."
The meaning of a thumbs-up emoji would be evaluated on a case by case basis in the context of the discussion purported to be creating a binding agreement. I suspect that this is also the true statement of Canadian law.
More generally, body language and gestures and images together with actual words can be considered by a court, in the overall context of an interaction, to determine what was communicated by the parties with each other in order to form a contract. Similarly, slang or non-literal uses of words could form a contract if their meaning is consistent with agreement in the context of the overall discussion.
These foundational concepts of contract interpretation and formation are shared by essentially all common law countries.