Much like the Bonk, the Halligan is also able to open doors. The Halligan is more used in America, while the Bonk is more used in the Netherlands. It can be found in the Firetruck. How to use it:
Just like the Bonk, the Halligan tool is supposed to be held with both hands. It can be picked up by reaching for it and pressing the trigger button on your controller. You should now grab the other side of the Halligan with your other hand.
You can use the Halligan to open a door regardless of whether it is open or not, but it is of course usually used to open a locked door. When you are standing next to a door, you can slam the Halligan against the door, which will also make a distinctive sound. It usually takes more than 1 hit to open a locked door. The number of times that you need to slam against the door is measured by how hard you hit it.