Using square bracket in text mode

You don't escape square brackets in LaTeX if you want them typeset. \[ and \] are basically synonyms for \begin{displaymath} and \end{displaymath}, (or \begin{equation*} and \end{equation*} with amsmath loaded), and will make the enclosed content typeset in a unnumbered displayed math equation on a separate line, which is clearly not what you want.

In conclusion you should simply write

[2007] EWCA Civ 1042

verbatim to get the output

[2007] EWCA Civ 1042

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Edit: As noted in the comments, this will not work in the special cases where the brackets follow a macro (as in \item [2007] EWA) or if it comes first in a row in a tabular. In these situations one should group the brackets inside braces as {[2007]} EWA.

You also could try this: {[2007]}

If [ and ] are causing trouble, just switch them out for \lbrack and \rbrack.