What do you call someone who is focused too much on the technicalities of a law rather than the big picture?

Question

What do you call someone who is focused too much on the technicalities of a law rather than the big picture? Some people are too much focused on the word by word definition of a law that they forget why these laws were put into place and use the definition to apply the law in a way it wasn't intended by the person who wrote the law. Is there a word for such person? You can use related words and maybe form a short phrase if there isn't any word for it.

For example:

The ____ used a technicality in the law to bypass it entirely.

Answer 1

Martinet - someone who demands that rules and orders always be obeyed, even when it is unnecessary or unreasonable to do so.

Pernickety - giving too much attention to small details that are not important in a way that annoys other people.

Pettifogging - Pettifogging people give too much attention to small unimportant details in a way that shows a limited mind.

Fastidious - a person who gives too much attention to details and is hard to please.

Answer 2

A "shyster" is a dishonest or unethical lawyer, and the term could be used for a lawyer who uses a technicality to evade the intent of a law and defeat the ends of justice. The term is negative, indeed insulting, at least as much so as "crook". The term very specifically means a lawyer, one cannot be a shyster without being, or at least acting as, a lawyer.

Definitions

• According to Merriam-Webster, a Shyster is:

  a person who is professionally unscrupulous especially in the practice of law or politics :

• According to the Urban Dictionary, the word is:

  Generally used to describe someone who is untrustworthy, money grabbing and full of crap, particularly in the field of legal work for some reason.

• According to Wikipedia a Shyster is:

  a slang word for someone who acts in a disreputable, unethical, or unscrupulous way, especially in the practice of law, sometimes also politics or business.

• According to Collins English Dictionary, a Shyster is:

  a person, esp a lawyer or politician, who uses discreditable or unethical methods

• According to the Oxford Dictionaries site, a shyster is:

  A person, especially a lawyer, who uses unscrupulous, fraudulent, or deceptive methods in business.

• According to [Dictionary.con] a Shyster is:

  1. a lawyer who uses unprofessional or questionable methods.
  2. a person who gets along by petty, sharp practices.

Answer 3

You could use rule-bound:

[Oxford Dictionaries]

ADJECTIVE
Overly limited or restricted by rules.

‘a complex and rule-bound system, difficult to understand, and hard to administer’

‘Classical and neoclassical methods were beginning to be seen as rulebound, overly strict, and not much like what real life is like.’

‘I must confess I did anticipate that his many years in the Civil Service would show that he might be rather rule-bound.’

‘The actions and behaviors of uncaring nurses were rule-bound and super-efficient; these nurses appeared tense, and they avoided eye contact with patients.’

The adjectival phrase can be applied to both things and people. There is no specific definition for it at Merriam-Webster yet, so it doesn't consider it common enough to be listed as a compound adjective rather than just the combination of two normal words.