He survived the reign of Henry VIII., that perilous age for the Howards, with no worse misadventure than the conviction of himself and his wife of misprision of treason in concealing the offences of his niece, Queen Catherine.
By listening to the revelations of the "Holy Maid of Kent," the nun Elizabeth Barton, he was charged with misprision of treason, and was condemned to the loss of his goods and to imprisonment at the king's will, penalties he was allowed to compound by a fine of X300 (25th of March 1534).
He soon distinguished himself by a speech in support of the Bill for Regulating Trials in Cases of Treason, one provision of which was that a person indicated for treason or misprision of treason should be allowed the assistance of counsel.
This arrangement has been partially abrogated by the Treason Act of William III., which in cases of treason and misprision of treason requires that all peers of parliament shall be summoned twenty days at least before every such trial.
Garnet was clearly guilty of misprision of treason, i.e.