This morning’s Observer column.

Many years ago, the Harvard legal scholar Lawrence Lessig coined the phrase “Code is Law” to express the view that, in a digital world, private fences erected via software can undermine public law in all kinds of unanticipated ways. The recent antics of our parliamentary authorities in relation to MPs’ expenses have provided us with an instructive case study of the Lessig principle in action.

Their chosen tool for controlling our access to information is the computer code embodied in the portable document format (PDF)…