This curse was brought in by our enemy sin. Adam, the first man, sinned by disobeying the commandment God had given him about the tree of the knowledge of good and evil. Immediately we then hear of a curse in the Earth. After that, as sin increased in the Earth, so the prevalence of the curse increased. The world witnessed what Paul put into words, The wages which sin pays is death.
Death here refers to far more than just the ending of our physical existence.
It refers to all the miseries arising from sin, both now and hereafter. In it we see how the curse brought in by sin manifests itself destructively in every facet of our human existence. You can read it in the 28th chapter of Deuteronomy starting in verse sixteen. The curse of the law is the Bible's label for all the distresses experienced as a result of sin. Today you can walk away once and for all from the curse of the law.