A tool to prevent crime and terrorism, in the hand of a government, seems to be a good thing on the face of it. But crime and terrorism are just other types of human activity. A system capable of preventing crime would have to be a system to prevent any type of human action the user of the system defines. With other words, it would have to be a tool of power.
There is no guarantee such a tool would be used in the interest of the citizens and not against them. Only a free and lawful democratic society can make sure such a tool is not used against it but that same free, lawful and democratic society is, at the same time undermined by the presence of such a tool.
A tool that can be used against terrorists can also be used against opposition members whose only “crime” it is to have a different opinion about what the government should do. Governments must be seen as service providers for the people, but given to much power, they will turn into tyranny.
A tool of power in the hand of a government must therefore be controlled. If it is not controlled, it will very likely be misused. Therefore tools of power in the hands of governments have to be restricted to the possible minimum and have to be controlled strictly and publicly. If the power of the government is not restricted, you are on the way to dictatorship and state terror.
In a democracy, the real sovereign is neither a president nor a monarch, it is the citizens. Secretly introducing means of power that can be used to suppress or prevent actions of citizens, and thus to increase the likelihood of the tipping from a lawful, constitutional democracy into a dictatorship, can and should therefore be viewed as an act of treason against the sovereign, maybe not in the sense this word is used in the legal codes of states but according to its original meaning. In such a case, the citizens must take action to restore the lawful constitutional order of the free, democratic state.
(The picture is from https://commons.wikimedia.org/wiki/File:Olympe_gouges.jpg. It is showing the beheading of Olympe de Gouges, a female author from the time of the French Revolution and author of Declaration of the Rights of Woman and the Female Citizen.)