Yes, basic contract law requires that both parties have to agree to the terms of the contract and, for a real estate sale, that agreement must be in writing and signed by both parties.
With a counteroffer, though, the seller already has signed the agreement and, by signing, is agreeing to all of its terms (including the time allowed for acceptance or rejection of the offer). The seller waits for the buyer to sign within that time.
When a seller wants to withdraw a counteroffer, timing (and the contract itself) can be critical.
A lawsuit can easily result if the seller tries to withdraw the offer and the buyer tells the seller he has already signed the agreement. The buyer has the advantage by having a written sales agreement that has been signed by both parties.
And thank you for the apology.
I will post back with cases later today - maybe not Florida ones - to better illustrate my comments to date. Facts, as always in law, matter.
Here is one to start off (
Dickerson v. Dodds, L.R. 2 Ch.D. 463 (1875-1876)), where the court held that a seller is free to withdraw an offer at any time before acceptance takes place
if there is no consideration:
http://www.thomsonreuters.com.au/product/AU/files/720502512/contract_p2_dickinson_v_dodds.pdf
And here is one from Florida (
Morrison v. Thoelke, 155 So.2d 899, Fla App 2 Dist, 1963), which speaks to the "mailbox rule":
http://www.invispress.com/law/contracts/morrison.html
And here is one from Kansas (
Berryman v. Kmoch, 221 Kan 304, 559 P.2d 790 (1977)), on option contracts and consideration:
http://law.justia.com/cases/kansas/supreme-court/1977/48-106-1.html