The War on Drugs is not only a failure, but it has become a self-perpetuating, constantly expanding policy disaster.
Be on your guard against the yeast of the Pharisees, which is hypocrisy.
Then they understood that he was not telling them to guard against the yeast used in bread, but against the teaching of the Pharisees and Sadducees.
The Drug War, and those who promote it, have made it go from a few people spending what probably was a few hundred thousand dollars, to employ tens or hundreds of thousands of people* and it has consumed over $1 Trillion dollars. The return on this "investment?" Death, the increased spread of disease, the increase of people with a financial incentive to spread addiction, the increased corruption of many thousands in government, a gross increase in imprisonment and shaming of millions of people who did not deserve that treatment, the spread of lies, the hiding of important and useful information, and every other evil fruit of the Drug War Tree.
It doesn't bring healing, it brings harm; it keeps patients from beneficial medicines. It doesn't keep drugs out of the hands of kids, it puts drugs in the hands of kids. It doesn't keep drugs out of prisons. It doesn't save lives, it causes people to die since dosages are not standardized. Prohibition doesn't decrease misery, it increases it exponentially to the factorial power!
Another thing the quote from Jesus teaches, is he didn't intend for everything he said to be taken literally; at times he spoke in metaphor and in parables. Thus, one should not strain one's self to try to interpret everything in the Bible literally.
If Jesus was speaking to us, in our time, he might not have used "yeast" since so many people do not bake their own bread; he might have used the word "cancer" instead. Both yeast and cancer are fast growing cells. Cancer, however, is always bad; it comes in two forms, malignant, which is really bad, and benign which is less bad. Yeast, however, as noted above, was used a metaphor; yeast is not always harmful or used negatively in the Bible. We see this in another parable of Jesus: Matthew 13:33-35.
At its outset, the DEA had 1,470 special agents and a budget of less than $75 million. Furthermore, in 1974, the DEA had 43 foreign offices in 31 countries. Today, the DEA has 5,235 special agents, a budget of more than $2.3 billion and 87 foreign offices in 63 countries.