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.