Rule 5 draft

First off, note that it's not the "Rule V Draft," but the Rule 5 draft. It's called the Rule 5 draft because the section of the Official Rules that covers the draft just happens to be Rule 5 in the book.

Eligibility: A player not on a team's Major League 40-man roster is eligible for the Rule 5 draft if: the player was 18 or younger when he first signed a pro contract and this is the fourth Rule 5 draft since he signed, OR if he was 19 or older when he first signed a pro contract and this is the third Rule 5 draft since he signed.

A player drafted onto a Major League roster in the Rule 5 draft must remain in the majors (on the 25-man active roster or the DL) for all of the subsequent season, or the drafting club must attempt to return him to his original club. However, since a returned Rule 5 player must first be placed on outright waivers, a third club could claim the player off waivers. But of course, that club would then also have to keep him in the majors all season, or offer him back to his original club.

Occasionally, the drafting club will work out a trade with the player's original team, allowing the drafting club to retain the player but send him to the minors.