Style guides are always fascinating. I wish I could forget about them, but various clients have different ideas about how they want English to be written, and on top of that I used to teach English grammar, which meant laying down some laws. Here’s the UK Government digital style guide (link updated Dec 2015).

This is weird:

2.17 Numbers

Write all numbers in numerics (including 1 to 9) except where it’s part of a common expression and it would look strange, eg ‘one or two of them’. Use common sense.

‘One of the 13 words in this sentence is causing problems: this 1.’

This sentence would be better with ‘one’ as the final word.

My rule would have been to write ‘thirteen’, and indeed to write all numbers up to ninety-nine in words (German often says to write from one to twelve in words, but even there I am constantly encountering ‘1.’ (‘first’) in the middle of quite serious and non-abbreviated texts). Of course the problem then arises, as it did for me recently in a translation about genetics, that when you are discussing statistics you should write all numbers as figures. But then there comes a bit of text where it’s no longer about statistics.

Also: write all numbers in numerics! they mean figures, I think.

But the idea of writing ‘this 1’ even in error never occurred to me!

Now down to legal style:

2.14 Legal language

If you’re talking about a legal requirement, use ‘must’. For example, ‘your employer must pay you the National Minimum Wage (NWM)’.

If you feel that ‘must’ doesn’t have enough emphasis, then use ‘legal requirement’, ‘legally entitled’ etc. For example: ‘Once your child is registered at school, you are legally responsible for making sure they attend regularly’.

When deciding whether to use ‘must’ or ‘legally entitled’ etc, consider how important it is for us to talk about the legal aspect, as well as the overall tone of voice.

If a requirement is legal, but administrative, or part of a process that won’t have criminal repercussions, then use: ‘need to’. For example: ‘You will need to provide copies of your marriage certificate’.

This may be a legal requirement, but not completing it would just stop the person from moving on to the next stage of a process, rather than committing a more serious offence.

They are obviously totally avoiding the word ‘shall’. Of course, ‘shall’ in that sense is only used in contracts and statutes, not in writing about them.

‘Need to’ if no criminal repercussions. I love it.