Not so much a legal code as a series of trade agreements and stipulations for said commerce.
The Cartric Republic, formerly the Holy Realms of the Cledic State, require a series of conditions to be met in order to truly benefit from their economic model and global trade connections. While certain quotas and other mundane numeric goalposts must be reached, the widest in scope and most heavily criticized requirement is the banning of magic in the nation that wishes to trade.
The HRCS was a colonial theocracy, spreading the gospel of the true creator and laying low those that worshipped heathen entities, all to save the souls of humanity from the temptations of darkness (I feel like I've heard this before...). The use of earthly magics was a tell-tale sign of said worship, and the magic frequently attracted or birthed shadowy corruptions that would periodically plague the land.
The HRCS was eventually transformed into a republic, but the resentment of magic was still deeply ingrained in the culture and government. The regions of the world they hadn't taken over outright would often capitulate for the lucrative technology that came from these anti-magic zealots, and often adopted many facets of Cartric/Cledic culture.
Exceptions have certainly been made, such as for the viceroyalties of Varhoste, as their deep mineral deposits are a great resource for the industrial Cartref, but the Varhoster mining infrastructure relies on stone weaving, an ancient magic practice. The deeply religious practice of stone weaving has since been restricted, requiring a license to use (for industrial and military use only), causing some discontent.