I have just received my copy of the second edition of Parliament and the Law, edited by Alexander Horne and Gavin Drewry. I have contributed a chapter, with Lucinda Maer, on ‘Relationship between the two Houses’. That relationship is shaped by the acceptance of the House of Lords that the House of Commons enjoys primacy and is characterised by constraints on the Upper House and by co-operation.
The constraints are to be found in statute, convention and practices. The first of these is straightforward, with the Lords constrained by the Parliament Acts. Conventions are rules of behaviour that are accepted as binding by virtue of constituting right behaviour. The defining characteristic is that they are invariable. The most obvious convention constraining the House is the Salisbury convention, enunciated in 1945 by the then Viscount Cranborne, but one derived from the referendal theory developed by his grandfather, the 3rd Marquess of Salisbury. Practices are exactly that and are distinguishable from conventions in that they constitute behaviour that is normal but not invariable. Falling under this heading are ‘ping pong’, financial privilege, statutory instruments and getting the Government’s business in reasonable time. Though some tend to elevate one or more to the status of convention, there is nothing that binds either House. Even in respect of ‘double insistence’ in conflicts between the two Houses, there is, as Erskine May records, no binding rule which governs proceedings in either House.
Both Houses constitute essentially discrete entities – the principal method of contact is by message – and conventions and practices have been developed in order to ensure that the relationship works relatively smoothly. There is a large element of trust. There are occasional tensions but, on the whole, it is a mature and effective relationship.