Once qualified as a barrister, Hendy established a law centre, the Newham Rights Centre in East London, and worked there full-time for three years. He then lectured for a year at
Middlesex Polytechnic, before returning to
the Bar in 1977 to focus on personal injury and industrial relations cases. In the mid-1980s, he successfully represented
Wendy Savage, a consultant obstetrician and
gynecologist who was suspended from practice for alleged incompetence. The case led to Hendy taking others in the area of medical negligence, discipline and ethics. In 1984–85, he represented the National Union of Mineworkers in the civil litigation arising out of the Miners' Strike. He
took silk in 1987. In 1991, Hendy was one of four QCs, along with
Michael Mansfield,
Geoffrey Robertson and Kevin Garnett, acting for the
National Union of Mineworkers against claims that they had handled funds inappropriately during the
miners' strike of 1984–85. In 1992 he represented mining unions in the
High Court against attempts to close 31 coal mines. In 1995, he acted for
National Union of Journalists (NUJ) member Dave Wilson in the
Wilson and Palmer v United Kingdom case that ended discrimination against trade unionists. In April 1999, Hendy became head of Old Square Chambers, in succession to John Melville Williams. By that year, judgments in 76 of his cases had been published in
law reports. Hendy retired as head of Old Square Chambers in 2009. In 2011 Hendy joined
UCL Faculty of Laws as Honorary Professor of Labour Law. He represented the NUJ at the
Leveson Inquiry and questioned
Rupert Murdoch directly on 27 March 2012. ==House of Lords==