This situation happens quite a lot at my club.

All four players in the group are looking for Player A’s ball. Another person (not Player A) spots a ball and asks Player A (standing nearby) what ball they are playing.

The other person then lifts the ball (without marking its position) to identify it. If it’s Player A’s ball, it is replaced.

Is this action OK? Namely, lifting another player’s ball without marking it, with that player nearby.

What is the applicable rule(s)?

Thanks, Peter.

Not on. Only the player or his caddy may lift the ball to identify it IIRC.

It is a bad practice and should not happen, BUT, in stroke play there is no penalty – R.18-4.

I assume we are talking about an indvidual stroke play type event.

The outcome is that the ball has been moved by an outside agency (fellow competitor – whether they are in your group or not doesn’t matter), there is no penalty to anyone and the ball is replaced.

See Rule 18/4

The outcome is different if the ball is moved by your opponent in mtachplay.

The outcome is different if the ball is moved by your opponent in mtachplay.

Or if the other person was your partner.

Yep the outcome is different if the person is your 4 ball partner but not in foursomes (when it will be his ball as well).