The Shield Against Weapons (SAW) is a railgun system that shoots down incoming enemy ships. It goes before other defensive measures such as drones and fighters, which can help save your drones and fighters for tougher battles. SAWs also help you defend your allies, as long as they are in the same star system as you. If an enemy ship is incoming to any world in a star system, then all allied planets will fire their saws at the incoming enemy ships.
Asteroids are defended by all SAWs in the system.
Uninhabited planets are defended by all SAWs in the system.
Inhabited planets are defended by all alliance-owned SAWs in the system.
Any non-alliance combat ship is considered an enemy ship by the SAWs. This means that a non-alliance colony ship will be considered an enemy ship and will be shot down. Fighters sent to defend a body will not be shot down as they are not an attack.
You are limited to Ten SAWs per planet. Having more than ten if you built them prior to the release that limited them to ten, will not benefit your defense.
SAWs now support each other, so the more SAWs in a system, the greater the combat value of each SAW in defense.
When an attacking ship triggers a systems defenses, the targetted body will respond first, but will receive a bonus for every supporting SAW. After comparing combat values, the SAW may recieve damage to it's efficiency. A low attacking value can still have a chance of causing a small decrease in efficiency.
If ships penetrate thru the first planet's SAWs, the other planets in the system will respond as well.
If efficiency has been lowered, the SAW will begin working with a 15 minute timer. However, it can still defend until it is reduced to 0%. After it finishes working, it will automatically attempt to repair itself. (The cost to repair is much lower than if a player repairs manually.)
Playing Note: If you have multiple planets in the same system with multiple SAWs per planet, this is sometimes called a "SAW Ring", or a "Ring of Fire". This provides the best automated defense setup you can get.
A Spaceport full of ships can defend nearly as well as a fully set system with SAWs. Exact limits have not been tested yet by players. (And of course, you can have both.)