The complexity and creativity of the private trade in medicines in colonial Vietnam manifested itself with particular intensity in the illegal practices reported by French authorities. As seen in Chapter 4, both state-qualified pharmacists and sellers of “traditional” medicines fought, vigorously and with ingenuity, to secure and expand their markets, flexibly adapting to new sources of influence and competition, to changing demand, and to the gaps and shortcomings of the public system. In this, they often tested the limits of legality, sometimes crossing the line into patently illegal practice, for which they were occasionally caught. Laws on the practice of medicine and pharmacy, on the importation and sale of toxic substances, and on trademark registration and infringement defined a number of infractions.