USBCルール
これも前に出てるとは思うが貼っとく。
先に言っておくが、読み比べるとNBRと同じだ。
右手でも左手でも投げる医学的必要性がある者についての規定は
このスレに関係ないが、省略しないでおいた。

Rule 4 ? Delivering the Ball
4c. Mechanical Aids to Grip the Ball - Alternating Delivery
A player may, if granted permission by USBC Headquarters
and each league or tournament in which the player participates,
alternate right/left-handed delivery and/or use special equipment
to aid in grasping and delivering the ball.

Permission may be granted if the following is submitted to
USBC Headquarters:
1. Alternating Delivery: A doctor’s certificate describing the disability
and the reason to alternate right/left-handed delivery.
2. Mechanical Aid: A description, drawing or model of the aid.
Unless the individual is unable to impart force or impetus to a ball,
the aid cannot incorporate a mechanical device with moving parts
that would impart force or impetus to the ball.
[USBC reserves the right to request a doctor's certificate.]

When authorization is given, USBC Headquarters will provide the player
with a special card stating that alternating right/left-handed delivery
and/or thre use of the specified mechanical aid has been approved.
If permission is denied, the player has the right of appeal to the USBC
Legal Committee.

Permission may be withdrawn for cause.