No medical, pharmaceutical, food or dairy products leave testing to the producers or vendors of these products. Why? The answer is obvious. Credibility. In contrast, 3rd party testing is reliable in a way that "self monitoring" can never be.

Currently, even the most basic safety and quality assurance practices are not required for Medical Marijuana. In response, several municipalities are developing ordinances that require dispensaries to have their products tested.  Some dispensaries test their medicine “in house”. This is a uniquely limited model when compared to either the pharmaceutical or food industries. If each dispensary chooses to test all of its’ own products, then the door is open for dispensaries to manufacture results or, even among the most well meaning of dispensaries, make mistakes.
 

Alternatively, testing Cannabis using an accreditted and certified third party agency would verify competence, prevent bias, and establish credibility. Each dispensary can then distribute medicine with the assurance that it has been certified as safe for consumption. Consistent with it's primary mission, a dispensary can empower its patients to make the correct choices in their medicine specific to their needs.

Can you tell which is the following samples is safe medicine?

Sample 1 - Cotton Candy Wrong!  Although this cannabis looks delightful, you can't tell it's safe just by looking at it.  The only way to tell is by testing it. Sample 2 - Blue Dream Wrong!  It's impossible to tell if cannabis is safe by simply looking at it.  The only way to tell is to get it tested.