On 28 December 2018 the Land and Environment Court of New South Wales decided the case of Hourigan v Howard  NSWLEC 1686.
The applicants claimed plants along the fence line obstructed sunlight to their property and sought a remedy from the court. The Trees (Disputes Between Neighbours) Act 2006 No 126 [NSW] ("the Act") empowers the court to "remedy, restrain or prevent a severe obstruction" (Part 2A) of sunlight to a window, or any view from a dwelling (section 14B).
The particular plants were found to have an average height of 2.5 m, with some new shoots reaching above 2.5 m. Therefore, Part 2A of the Act applied.
Relevantly, in winter only part of the lower section of the affected windows was obstructed; there was no obstruction of sunlight for the remainder of the year. Consequently, the court concluded the obstruction of sunlight was "not severe" and therefore the court could not make any orders relating to the offending trees.
If you are considering an application to "remedy, restrain or prevent a severe obstruction" to sunlight to your windows or a view from your house caused by trees on your neighbour's property, the height of the offending trees must exceed 2.5 m and the obstruction of sunlight must be severe.