There is a whole industry of Drug War sponsored quack science that is no more legit than tobacco company sponsored "science."

There is plenty of objective, non-sponsored research that shows marijuana to have at least in some cases a negative effect. But nice work blanketing all of the research you disagree with as illegitimate.

Then link it.

EDIT: From last time we talked about this, some Google Scholar links--

http://www.sciencedirect.com/science/article/pii/S0890856709....

http://bjp.rcpsych.org/content/180/3/216.short

http://www.bmj.com/content/325/7374/1195.1.short

http://www.sciencedirect.com/science/article/pii/S0022395607....

Note, though, that these are pretty inconclusive as far as causality goes.

I painted it as illegitimate because it is. ONDCP does propaganda, not science.

Subsequently debunked as an uncontrolled study. That's a prime example of the kind of research and researchers bought by ONDCP.

Citation for this debunking?

Here: http://www.pnas.org/content/early/2013/01/09/1215678110.abst...

And, as a bonus, here is a debunking of a similar, and similarly widely touted study that made it into the Lancet. http://www.ncbi.nlm.nih.gov/pubmed/19560900

The point is: The whole purpose of these heavily funded studies is to penetrate mainstream journals. They were hyped in the mainstream press with the full weight of government behind the press blitz.

There isn't actually good evidence to distinguish the flow of causation with cannabis and schizophrenia. In a significant plurality of cases, schizophrenia manifests in the 15-21 age range, regardless of cannabis use.