When and why do lawyers use italics in a document. There really is no consistent explanation.  Traditionally, italics are used in:

• Titles of legal and other scholarly articles – for the title, but not the author’s names or the citation – i.e., the information that allows someone to track the article down (but not consistently for books titles, for which small capital letters are often used);
• Case names – so in the long version of the name – i.e., Bob Smith v. Acme Dangerous Products, Ltd., and the short version of the name, i.e., Smith which is usually used after the first full citation of the case; and
• When a term is used that comes from a foreign language to the term in the text, so for example ex parte or inter alia which are Latin.  Curiously, certain words that are probably of old English origin such as estoppel and laches are also often italicised in English; this may be a result of confusion as to their linguistic origin.

Because a lot of reference and cross-reference words like supra (above), infra (below) as well certain short forms such as e.g. (exempli gratia meaning ‘for example’) and i.e. (id est usually meaning ‘that is to say’ or ‘in other words’) and id. (idem meaning the same)) are originally Latin, they are also often, but not consistently italicised – and the habit seems to have led to the frequent italicisation of ‘see‘ when used in a reference.