Where deft's trial counsel was preoccupied with vindication of a manifestly weak legal theory and the issue is not raised in state habeas -- the latter is ineffective assistance by its terms, and the former is a sufficient showing -- cause for waiver in subsequent federal collateral challenge is excused.
http://www2.ca3.uscourts.gov/opinarch/161969p.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.