Technically, yes, this can happen: a favorable ALJ decision can be overturned by the appeals council.
However, this can be thought of in the same manner as the risk of an airline crash; that is to say that, while it can happen, it is unlikely to happen to a social security disability or SSI disability claimant who has been approved for disability benefits.
The appeals council (and this particular level in the ssd and ssi appeals process may be eliminated at some point in time) can review the decisions of administrative law judges much in the same way that DQB, or the disability quality branch, reviews the decisions made by DDS disability examiners. In either case, though, the percentage of cases pulled for such review is very small. Likewise, the chance of a disability approval being overturned is also very small.
And, in fact, the vast majority of social security disability cases that are sent to the appeals council are sent there at the request of an attorney or non attorny representative following a denial of a claim by an administrative law judge.
