she was saying that if someone attacks you, in any way, you are only legally "allowed" to use the exact same type of force in defense. that blew my mind
She understands the premise of the law, but not the law itself, or other factors that change things.
Deadly force is deadly force. A knife is deadly force. A rock is deadly force. A 2x4 is deadly force. A baseball bat is deadly force. Essentialy any weapon which is not intentional made for use as less lethal force, and can inflict lethal injuries is deadly force.
If you believe yourself to be at risk of immediate life threatening injuries you can use your weapon.
That does not mean they simply have the weapon, but that they are actualy going to use it immediately.
There is also a disparity of force to be considered in some situations.
The same circumstances also change in different states, and in different locations. Someone breaking into your house for example would be held to a lesser criteria than a guy on the street. You can presume an armed intruder to be a lethal threat in most places, and even an unarmed intruder many places.
On the street you need to actualy feel the individual is likely to use it, and be in fear for your life. So some cases would be clear cut, but others might not be.
Now what she said is still worth thinking about if applied to someone with lets say pepperspray or a taser commiting a robbery or attack.
If someone pulls out or uses pepperspray or a taser on you and you have a firearm, can you or should you reply to non lethal force with lethal force while you still can.
A LEO would, but LEO policy is to use one level of force higher, not to match with equal force.
Or should you allow yourself to succumb to the effects over time and the other person gain the upper hand, possibly gaining control of or taking possession of the firearm themselves in the course of the robbery or attack when you no longer have that discretion.
You also need to know right and wrong. The law is not a substitute for morals, even though many would like it to be.