Small businesses for sale transactions are known to have a low escrow closing rate, for a number of reasons, either landlord issues, franchisor qualifications not being met, or state and government agencies getting involved which could kill the deal, and this doesn't even include squabbles among buyer and seller over other issues that may arise. Most often it's the buyer who wants to cancel escrow, because the renegotiation of a new lease is not acceptable or they simply get cold feet and decide they don't want to buy the business. Many businesses are so difficult to sell and find the right buyer, and yet every so often, it's the seller who changes their mind and decides they don't want to sell, because perhaps they were getting a divorce and put the business up for sale but have since reconciled the relationship and want to keep the business, or a health issue has been cleared and they want to retain ownership. This can be maddening for both the broker(s) involved and buyer, and some buyers will ask, "Can they just do that?"
Can a seller back out of an escrow? Probably, yes, it all depends how far along the escrow is, which will dictate how messy things will get. If the lease has been signed by the buyer, then I'd suggest both buyer and seller talk with an attorney. The seller just backing out of the escrow, while all contingencies are being met would be a breach of contract. The only way they could do it legally is if it was specified to the buyer that this particular escrow is contingent upon the seller obtaining another business which is in escrow, etc. Most sellers have obtained a reasonable exit strategy by the time they are deep in escrow and have had their business on the market, but in life, things can and will change.
I use CAR (California Association of Realtor) forms for my transactions, but some brokers use their own forms, so I' d suggest that when a buyer signs contracts, to read them very carefully to make sure that there are no contingencies placed in by the seller. A buyer should also make sure to diligently sign every page. My contracts stipulate that issues between buyer and seller will be mediated before civil action takes place, in hopes that it can be worked out before it gets expensive. The seller may be on the hook for a buyer's legal fees, any inspection fee paid by the buyer during the transaction, and other fees, and so each party should consult with an attorney who specializes in the field of business litigation. The seller may also be sued by the business broker for a commission since they did find a ready and able buyer who was willing to go through with the transaction.
Can a judge force the seller to sell the business to the buyer? Probably not, but again each party should consult with an attorney. Of course, forcing someone to do something would garner a negative response, like objecting to do repairs that had previously been agreed upon by both parties or simply harming the goodwill of the business out of spite.