Before the shell casings have time to cool the same people are calling for more gun control. Their solution for mass killings is to disarm all of the law abiding citizens so everyone can feel better about themselves thinking they did something. The people calling for these new laws are the same people that fight for the right to murder a million babies a year so it is hard to take them seriously when they complain about a lot of people being killed. Perhaps if we simply relabeled these mass shootings as post-natal abortions it would be more acceptable to certain people. The problem is that taking guns away from law abiding people does not change the way potentially dangerous people feel. If they want to hurt someone, they will find a way.
When these things happen we immediately see new legislation to try to curb the ability of people to commit these types of crimes. New red flag laws are one of the things being pushed today as a cure all. The idea is to identify people who might pose a threat to society and take away their guns before they can do something. The problem is that laws such as this only apply to certain people in practice. Are police officers, government agents and certain politicians going to be relieved of their weapons if they are accused of being a threat by someone? I seriously doubt it. These types of laws are only to disarm those the government wants to disarm.
The other problem is that Congress can pass any laws that it wants to but any law that is repugnant to the Constitution is automatically null and void. They have no legal authority to enforce it and citizens have no legal obligation to obey it, and this does not even take into account the due process issues.