A ball point pen dispenses ink by the little ball rotating. So the lid is more to prevent that happening than to stop the residual ink dying. That said, the on

A ball point pen dispenses ink by the little ball rotating. So the lid is more to prevent that happening than to stop the residual ink dying. That said, the only time I've ever had a ball point leak is when the ball is upwards and the ink reservoir opening down, so I would always put the lid on and pop it in the pocket lid down, making a mockery of the clip.