If R1 is caught between first and second after a fly ball drops, what is the outcome?

When a fly ball is caught, it results in a force out situation for any runners occupying bases. In this scenario, R1, who is caught between first and second base after the fly ball drops, is subject to the reinstatement of a force out.

Once the ball is caught, R1 must return to first base because the force is reinstated—meaning that R1 is now required to advance to second base at risk of being put out. Since R1 is caught in between the bases at the time the ball is caught, they are considered to be in jeopardy of being tagged out.

R1 being caught in between the bases means that if the defensive player with the ball tags R1 before they can return to first base or successfully reach second base, R1 will be called out. Therefore, since a force is in play, this outcome leads to the conclusion that R1 is out due to the reinstatement of the force play.