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From: Matt Whitlock <bip@mattwhitlock.name>
To: Danny Thorpe <danny.thorpe@gmail.com>
Date: Tue, 26 May 2015 16:18:06 -0400
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Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] Cost savings by using replace-by-fee,
	30-90%
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On Tuesday, 26 May 2015, at 11:22 am, Danny Thorpe wrote:
> What prevents RBF from being used for fraudulent payment reversals?
> 
> Pay 1BTC to Alice for hard goods, then after you receive the goods
> broadcast a double spend of that transaction to pay Alice nothing? Your
> only cost is the higher network fee of the 2nd tx.

The "First-Seen-Safe" replace-by-fee presently being discussed on this list disallows fraudulent payment reversals, as it disallows a replacing transaction that pays less to any output script than the replaced transaction paid.