precision, precisian

Precision or precision means exactness or accuracy --
This must be measured with precision, or the machine will break down frequently.
With practice, you'll be able to aim this with precision.

Precisian or precisian means someone who strictly follows the letter or rules of a code of belief --
He is a precisian, like an old-time Puritan, always quoting a rule, but lacking a sense of charity.
She chastised the precisian, and called him a hypocrite and a Pharisee.

Now that you know that, you can say--
"A precisian would insist on adhering to the letter of the law with precision."