Differences in court case citation in the US and UK (and in other Commonwealth countries) may sometimes be a source of confusion. As an example, in the US a civil action is generally styled “Smith v. Jones,” Smith being the plaintiff (demandante, now known as the claimant in England and Wales) and Jones the defendant (demandado). The case name is read aloud as “Smith versus Jones.” In England that same civil case would be written in the same way (Smith v. Jones), but would be read aloud as “Smith and Jones.”

Criminal cases in the US are easily identified by the fact that the first party, represented by the prosecutor or district attorney (fiscal), is the government, whether federal or state, as in the “United States v. Jones” or the “People of the State of Michigan v. Jones.” Here , as in civil cases, “v.” is also read aloud as “versus.” In England and in other Commonwealth countries criminal cases are prosecuted by the Crown in the name of the monarch, and therefore this same  case would be styled “R v. Jones,” “R” standing for the Latin “Regina” (queen) or “Rex” (king). However, the case name would be read aloud as “The Queen against Jones” (and not “The Queen versus Jones”).

In the US “v.” is sometimes read aloud as “vee,” rather than “versus” (pronouncing “v.” like the letter “v”), although legal linguist Bryan Garner cautions against this practice in his “Garner’s Dictionary of Legal Usage” (Oxford, 2011).

Read more here:

https://web.library.uq.edu.au/node/1712/7

http://web5.uottawa.ca/www2/rl-lr/eng/legal-citations/1_2-content_form_function.html