on the front line of
on the front line of somethingalso on the front lines of something
leading others in an effort to change something For years the group has been on the front line of efforts to educate people about global warming. Doctor Tay is on the front lines of improving treatment for people with head and spinal injuries.
Etymology: based on the military use of soldiers on the front line or front lines (closest to the enemy and very important but also those most likely to be hurt or killed)