The "old-fashioned methods" that they used in the past included intercepting communications of people that were suspected of crimes, such as by getting a warrant allowing them to force the person's phone company to record and turn over the person's calls, or by getting a warrant to intercept and inspect the contents of the person's mail at the post office.
> To outlaw large sections of mathematics because of this is absurd
No one has or is proposing outlawing large sections of mathematics, or even small sections of mathematics. The laws are outlawing some applications that make use of mathematics.
Calling that outlawing mathematics is as absurd as saying that building codes that won't let me use asbestos insulation in new construction are banning sections of thermodynamics. Or saying that laws that restrict how high I can fly a drone are banning large sections of aerodynamics.
