Jonathan Adler has a summary at the Volokh Conspiracy.
The Patient Protection and Affordable Care Act's Independent Payment Advisory Board has been called a "death panel," though I've argued one could just as legitimately call it a "life panel." Either way, it is the most absurdly unconstitutional part of the PPACA.
Adler's otherwise excellent summary neglects to mention IPAB's most unconstitutional feature. Diane Cohen and I describe it here:
The Act requires the Secretary of Health and Human Services to implement [IPAB's] legislative proposals without regard for congressional or presidential approval. Congress may only stop IPAB from issuing self-executing legislative proposals if three-fifths of all sworn members of Congress pass a joint resolution to dissolve IPAB during a short window in 2017. Even then, IPAB’s enabling statute dictates the terms of its own repeal, and it continues to grant IPAB the power to legislate for six months after Congress repeals it. If Congress fails to repeal IPAB through this process, then Congress can never again alter or reject IPAB’s proposals...
Congress may amend or reject IPAB proposals, subject to stringent limitations, but only from 2015 through 2019. If Congress fails to repeal IPAB in 2017, then after 2019, IPAB may legislate without any congressional interference.
Like I said, absurdly unconstitutional. But that's ObamaCare for you.