What's to stop counterparties to a contract from later marking up their copy with changes and forging initials, or swapping signature pages from one contract to another?

Context here is executing will of relative, who owned commercial rental property. On file with accountant and bank, I have seemingly clean printed original signed copies with two signatures.

And from one tenant I have marked up copies with changes very favorable to them (scratching out scheduled rent increases in future years, property tax increase allocations, and payments for shared utilities). Tenant says he never would have signed the original lease.

Are the latter documents part of the back and forth during negotiation? Or did decedent grant concessions without telling bank? (Bank required those clauses for the financing).

(Of course am consulting a real attorney, with actual documents, etc. Just my curiosity is getting the better of me in meantime.)

  • 2
    Basically, nothing, just as there's nothing stopping a person from robbing a bank. It is against the law.
    – user6726
    Jun 28, 2016 at 0:09
  • Do the business records show a history of one rental schedule or the other?
    – user662852
    Jun 28, 2016 at 12:52

2 Answers 2


Normally with a signed contract both parties get a copy as signed by both parties. That will be the canonical binding agreement. All parties are assumed to check that both copies are the same before they sign.

If a draft of the contract was used to negotiate over then it's common practice to print out a new contract with the agreed upon changes and sign that.

If after signing a new agreement is negotiated then a new contract should be made referencing the old one.

If I were to make a ruling over this I would say that the tenant made the alterations to his copy after it was signed and rule that the agreement is as laid out in the clean copy. But I'm not a judge and have never studied contract law (or any law) so that's not worth much.


Unless the parties take steps to make forging the contract more difficult, only the law exists to discourage that sort of behavior.

You can take certain measures to make doing what you're suggesting more difficult. With some work you might even be able to work out a scheme with a provable level of security. Some measures you can take to avoid this include:

  • Get a notary and/or other individuals to witness the agreement. Provide identical (maybe notarized) copies to the witnesses.

  • At the bottom of each page of the agreement, print a cryptographic hash of the contents of the previous page of the agreement (e.g. where each page is its own PDF file). Add language to the signature so that both parties must acknowledge this has been done and that they have confirmed the cryptographic hashes of each page.

  • Have each party initial, number and date each page of the agreement. Possibly each section as well. Add language to the signature page so that both parties must acknowledge this has been done and that they have confirmed all pages have been properly marked by both parties.

  • Make the agreement one page in length and sign/date along the top, bottom and margins. Or sign/date each page as such. Add language to each page so marked that the page is only valid of so marked by both parties.

I am not a lawyer and this is not legal advice - just some thoughts on how someone concerned about these issues might try to avoid them when drafting agreements for their own affairs.

  • From a legal POV, what does it mean for an ordinary citizen to "confirm a cryptographic hash" of a document? 99.99% of the time, that would be a false statement.
    – user6726
    Jun 28, 2016 at 16:02
  • @user6726 My intention was that all parties would compute the cryptographic hash of each page according to the method agreed to on the signature page, verify the hash at the bottom of page n+1 is equal to the hash of page n's contents (including or excluding hash on page n, as outlined) and agree that the hashes are all in agreement. Of course the parties would need to know how to do that for the scheme to work; is that your point?
    – Patrick87
    Jun 28, 2016 at 16:29
  • Yes, and there could be an issue of establishing that the parties comprehended what this means, i.e. this isn't your typical "Yeah whatever" EULA click-through.
    – user6726
    Jun 28, 2016 at 18:49

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