Black Techology is the term that refers to a set of technology and science that is forbidden in Guilty Gear.
In the 21st century, the urgency to preserve the environment became critical, and forced scientists to discover alternate methods of advancement. With the discovery of magic in 2010, mainstream science began to be taken over by magical science. Eventually, mainstream technology was banned by the UN and the term "Black Tech" was coined. The IPF became in charge in regulating technology and people who are selling, using or owning Black Tech is penalized. It's also illegal to spread knowledge about Black Tech. The only exception to this policy is the nation of Zepp.
The entirety of the technological ban eventually result in the creation of magi-tech to replace conventional technology, which vehicles are now powered by magic or firearms now used magical elements as ammunitions. The best example is the US infantry is shown to carry magic rifles or the US president uses a magic-powered limo for transportation. In the Guilty Gear X Drama CD, a drunk Axl who mentioned the E=MC^2 was almost arrested by the police.