In the early 19th century, a common German-speaking economic area emerges. This is accompanied by the unification of the bill of exchange legislation towards the general German bill of exchange regulation of 1849. This regulation does not commit to any specific legal concept, leaving room for the emergence of numerous different theories of bill of exchange law. At the same time, due to economic developments, the importance of bills of exchange in the business world increases. The theorists of bills of exchange also face the problem of how the newly introduced legislation, such as the ADHGB and the BGB, can be harmonized with existing laws. These theories are examined for their significance in commentaries and essays from the newly published commercial law journals. Key issues such as the legal classification of the draft, endorsement, acceptance, and negotiability are addressed. Additionally, the sometimes vehement discussions among the parties involved are traced. The result is that each theory possesses a certain plausibility, and concepts such as unilateral contracts and legal appearances are gradually accepted by academia.