The DEA has the power to schedule newly developed, dangerous synthetic drugs without immediate congressional oversight, the idea being that chemists can design and bring to market new, dangerous drugs more quickly than Congress is able to act.
They overstepped their authority in attempting to schedule kratom, as it is old, natural, and not particularly dangerous.
The idea that law enforcement agencies must be able to write their own law on the fly is the root of a lot of evil, not just in this case. Usually, they're not really in a hurry. They just want less oversight.
We can't wait for Congress because Congress is too slow! (Well, this one does make some sense as Congress seems to be deadlocked all the time...)
We need warrantless wiretaps and NSLs because it takes too long to get a warrant!
We need to detain people without a warrant because, again, we have no time to go find a judge!
We need to torture these terrorists because the next attack might come any minute and who doesn't like Jack Bauer?
They overstepped their authority in attempting to schedule kratom, as it is old, natural, and not particularly dangerous.