user17004: 

We started to use the Monrad system:
https://rankedin.ladesk.com/043159-2152--Monrad
https://en.wikipedia.org/wiki/Swiss-system_tournament
We are organizing a monthly tournament valid for ELO rating of the United States Chess Federation (USCF). The rating of our players is in the range 2000-400. We play a maximum of 3 rounds. Usually, we have between 8 and 16 players. This is an amateur tournament, in other words, no cash prizes. Players who achieve 3 points get a gold medal, 2 points a silver medal, and 1 point a bronze medal. We found that the classic Swiss system produces that a big percentage of the lower players retired from chess.
In my experience, in a game with a rating difference of 400 points, the lower rating player has a minimum of 90% chance to lose. In general, that will occur.
For that reason, we started to use the Monrad system.
If the highest rating is number 1, and the lowest rating is number 16. Without considering colors, the Swiss system produces 1-5, 2-6, 3-7, 4-8. But the Monrad system 1-2, 3-4, 5-6, 7-8.
The Monrad system is great because our main goal is to have a pairing with the smallest ELO rating difference possible. However, is it legal to use it for an USCF open tournament? It will be announced in advance. So, the players will know about it before to register. Our tournaments do not offer cash prices.
My main interest is in USCF. However, I would also like to know if it is legal for the International Chess Federation (FIDE).
As far as I know, the tournament organizer can use any system, if it is announced in advance and if it is NOT a national or international championship with established rules that the tournament organizer needs to follow.
Thank you for everything!

user12629: According to the FIDE handbook C.04.2 General handling rules for Swiss Tournaments:

1 The pairing system used for a FIDE rated Swiss tournament should be one of the published FIDE Swiss Systems.
Accelerated methods are acceptable if they were announced in advance by the organizer and are published in section C.04.5.


2 In derogation of the previous rule, unpublished pairing systems or accelerated methods may be permitted, provided that a detailed written description of their rules:
be submitted in advance to the Qualification Commission (QC) and temporarily authorized by them; and
be explicitly presented to the participants before the start of the tournament.

So, it appears that in FIDE you need prior approval to use a non-standard system.
In the USCF, rule 26B states:

A variation sufficiently major that it might reasonably be expected to deter some players from entering should be mentioned in any Chess Life announcement and all other detailed pre-tournament publicity and posted and/or announced at the tournament.

So you don't need prior approval, but you do need to let the players know in advance.

17004: <p><a href="https://i.stack.imgur.com/ZXMxs.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZXMxs.jpg" alt="Monrad system image" /></a></p>
<p><a href="https://i.stack.imgur.com/ge1Bz.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ge1Bz.jpg" alt="Monrad system rules" /></a></p>
<p>We started to use the Monrad system:</p>
<p><a href="https://rankedin.ladesk.com/043159-2152--Monrad" rel="nofollow noreferrer">https://rankedin.ladesk.com/043159-2152--Monrad</a></p>
<p><a href="https://en.wikipedia.org/wiki/Swiss-system_tournament" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Swiss-system_tournament</a></p>
<p>We are organizing a monthly tournament valid for ELO rating of the United States Chess Federation (USCF). The rating of our players is in the range 2000-400. We play a maximum of 3 rounds. Usually, we have between 8 and 16 players. This is an amateur tournament, in other words, no cash prizes. Players who achieve 3 points get a gold medal, 2 points a silver medal, and 1 point a bronze medal. We found that the classic Swiss system produces that a big percentage of the lower players retired from chess.</p>
<p>In my experience, in a game with a rating difference of 400 points, the lower rating player has a minimum of 90% chance to lose. In general, that will occur.</p>
<p><em><strong>For that reason, we started to use the Monrad system.</strong></em></p>
<p>If the highest rating is number 1, and the lowest rating is number 16. Without considering colors, the Swiss system produces 1-5, 2-6, 3-7, 4-8. But the Monrad system 1-2, 3-4, 5-6, 7-8.</p>
<p>The Monrad system is great because our main goal is to have a pairing with the smallest ELO rating difference possible. However, is it legal to use it for an USCF open tournament? It will be announced in advance. So, the players will know about it before to register. Our tournaments do not offer cash prices.</p>
<p>My main interest is in USCF. However, I would also like to know if it is legal for the International Chess Federation (FIDE).</p>
<p>As far as I know, the tournament organizer can use any system, if it is announced in advance and if it is NOT a national or international championship with established rules that the tournament organizer needs to follow.</p>
<p>Thank you for everything!</p>
 12629: <p>According to the <a href="https://handbook.fide.com/chapter/C0402" rel="nofollow noreferrer">FIDE handbook</a> C.04.2 General handling rules for Swiss Tournaments:</p>
<blockquote>
<p>1 The pairing system used for a FIDE rated Swiss tournament should be one of the published FIDE Swiss Systems.
Accelerated methods are acceptable if they were announced in advance by the organizer and are published in section C.04.5.</p>
</blockquote>
<blockquote>
<p>2 In derogation of the previous rule, unpublished pairing systems or accelerated methods may be permitted, provided that a detailed written description of their rules:<br />
be submitted in advance to the Qualification Commission (QC) and temporarily authorized by them; and<br />
be explicitly presented to the participants before the start of the tournament.</p>
</blockquote>
<p>So, it appears that in FIDE you need prior approval to use a non-standard system.</p>
<p>In the USCF, <a href="https://new.uschess.org/sites/default/files/media/documents/us-chess-rule-book-online-only-edition-chapters-1-2-9-10-11-8-23-21.pdf" rel="nofollow noreferrer">rule</a> 26B states:</p>
<blockquote>
<p>A variation sufficiently major that it might reasonably be expected to deter some players from entering should be mentioned in any Chess Life announcement and all other detailed pre-tournament publicity and posted and/or announced at the tournament.</p>
</blockquote>
<p>So you don't need prior approval, but you do need to let the players know in advance.</p>
