How do DUIs related to marijuana affect approval?

My brother just got a RFE indicating he had been convicted of possession of Marijuana, and driving under the influence of Marijuana. It's technically a DUI so is that reason for him to be automatically denied?

EEEH, its a pretty bad offence. DUI is DUI and its frown upon the eyes of the Government. Does he have a Felony? More offences? Remember, 3 or more misdemeanors and or a felony with 1 or more year in prison is an automatic denial. 1 offence is not, but seeing as how some USCIS employees belong to certain Unions, then they would definitely scrutinize his chances. Comply with the RFE, theres nothing more you can do. Good luck.

You may request consideration of deferred action for childhood arrivals if you:

7. Have not been convicted of a felony, significant misdemeanor, three or more other misdemeanors, and do not otherwise pose a threat to national security or public safety.

source

Q3: What offenses constitute a significant misdemeanor?
A3: For the purposes of this process, a significant misdemeanor is a misdemeanor as defined by federal law (specifically, one for which the maximum term of imprisonment authorized is one year or less but greater than five days) and that meets the following criteria:

Regardless of the sentence imposed, is an offense of domestic violence; sexual abuse or exploitation; burglary; unlawful possession or use of a firearm; drug distribution or trafficking; or, driving under the influence; or,

source

With some bad luck, a DUI can even cause a person with a green card to be deported. It doesn't look good for your brother.

What are they asking for in the RFE?

Surely they would have denied him if that showed up on his record? Can they not see the conviction?

I think he hasn't gotten the letter asking what they need but interesting if the RFE is not about these charges

The DUI WILL make an approval difficult but USCIS will still consider all the circumstances. If there is a lot of positive things that outweigh the bad, he may still be approved. Don't lose hope. He should have consulted an immigration lawyer prior to applying.