The Wall is primarily protected by scheduling under the terms of the Ancient Monuments and Archaeological Areas Act 1979. This is a statutory instrument, but the Wall was also inscribed as a UNESCO World Heritage Site in 1987.
Earlier statutory protection was found to be flawed when, in 1931, a claim on mineral rights led to the threat of the central sector of the Wall being quarried to within ten feet of the curtain wall itself, thereby potentially destroying its context within the landscape and posing a very real threat of collapse through landslip. The legislation was revised and Hadrian’s Wall was saved.
Further reading: Leach and Whitworth 2011