The taser rifles were in service of multiple branches of InGen security by 2015, including the Isla Nublar Incident of 2015.
The InGen Taser Rifle is usable by many playable characters, including Barry, Katashi Hamada, Raptor Handler Jenny, and the male and female ACU troopers. It can also be wielded by Trooper class custom characters.
It functions like any other firearm in the game, but can be used to hit electrical switches.
Gray and Zach Mitchell use taser rifles against the Velociraptors under the leadership of Indominus rex in the 3rd half of the level "Under Attack". Any playable character that the player chooses will be armed with this rifle in the Free Play of this level section. Similarly in the Free Play of this level, the player on the back of the Jurassic ATV in the last section of the level will also be armed with this rifle to fight the raptors.