The background of the change is a little complicated. There has always been a (minority) school of thought holding that writing a move down and then changing it, or even writing the move before playing it, amounted to “use of written notes.” Fischer made this argument back in the 60s, though he didn’t have much success.
In 2006 an electronic scorekeeping device called the “MonRoi” came on the market. Exactly why one would prefer a $400 PDA to a $.01 scoresheet is a good question, but some did. (The device was originally intended for invitational tournaments where the organizers would supply them, but that’s another story.) On the MonRoi, “writing” a move meant moving the piece on a small digital board, so “changing” one’s move really did amount to analyzing on another board.
The obvious solution would have been to make a special rule for electronic scorekeeping devices, but that’s not what the USCF did. Instead, the Rules Committee recommended (and the Delegates adopted) a sledgehammer approach, requiring all players to move before writing. The effect was somewhat vitiated by the fact that the recommended penalty was a warning.
Over the following year, there were a number of complaints about this, from players who didn’t want to change their habits and from TDs who didn’t want their time wasted with frivolous disputes. At the 2007 Delegates Meeting, the rule was changed yet again. The “basic” rule remains that one must move before writing, but a “variation” was added, which I suspect most TDs will use:
15.A. (Variation 1) Paper
scoresheet variation. The player
using a paper scoresheet may
first make the move, and then
write it on the scoresheet, or vice
versa. This variation does not
need to be advertised in advance.
TD Tip: TD’s may penalize
a player that is in violation
of 20C. “Use of notes prohibited”
if the player is first writing the
move and repeatedly altering that
move on their scoresheet before
completing a move on the board.
So, we’re right back where we started.