Assizes

The assizes date back to the 12th century and by the middle of the 16th century they had developed six circuits under the control of the Clerk of the Assize. The court normally met twice a year in each county in Lent and Summer, but by the middle of the 19th century a third Winter circuit was introduced to cope with the number of cases. They dealt with the more serious criminal offences (as well as some civil actions) not normally handled by the local court of
Quarter Sessions.
The Assize Courts were only abolished in 1971 when they were replaced by Crown Courts (in Manchester and Liverpool this had already occurred from 1956).

Assize Court records are held at the Public Record Office
and you should read their guide to Criminal Trials at the Assizes.
They are arranged by assize circuit and then by record type. The Oxford Circuit covered Wolverhampton (then part of Staffordshire) and was in existence from 1558 to 1971. There is no personal name index to the records and to locate a case you will need to know the name of the accused, approximate date of trial and the county or circuit in which they were tried. For the 19th century you could also try searching the Criminal Registers for England and Wales 1805-1892, also held at the Public Record Office, which list those charged with indictable offences and includes place of trial, verdict and sentence. For further details see their guide to
Tracing 19th Century Criminals in the PRO

Microfiche copies of the registers for Staffordshire & Shropshire1805-1816 are also available at Wolverhampton Archives & Local Studies.

Another useful source are the Calendars of Prisoners tried at the assizes, again held at the Public Record Office. The Staffordshire Assize Calendars 1842-1843 have been published in :

Collections for a History of Staffordshire (Fourth series, vol. 15)

a copy of which is available at Wolverhampton Archives & Local Studies.