His uncle sued to get back stolen land, and the court removed Uhuru's name, supposedly on the grounds of presidential immunity. This happened some time ago, but a case still continues against Ngina:
http://www.the-star.co.ke/news/uhurus-uncle-sues-over-old-land-grabWhat the questionable court ruling did not bother with is the difference between criminal and civil proceedings and the conditions attached to the latter.
Here is the relevant article of the Kenyan Constitution:
143. (1) Criminal proceedings shall not be instituted or continued
in any court against the President or a person performing the functions
of that office, during their tenure of office.
(2) Civil proceedings shall not be instituted in any court against
the President or the person performing the functions of that office
during their tenure of office in respect of anything done or not done in
the exercise of their powers under this Constitution.
(3) Where provision is made in law limiting the time within
which proceedings under clause (1) or (2) may be brought against a
person, a period of time during which the person holds or performs the
functions of the office of the President shall not be taken into account
in calculating the period of time prescribed by that law.
(4) The immunity of the President under this Article shall not
extend to a crime for which the President may be prosecuted under any
treaty to which Kenya is party and which prohibits such immunity.
Note that there is no absolute bar to civil proceedings against a president. Note the underlined. According to the High Court, Uhuru's grabbing land before he became president is now part of actions he has taken in exercise of .... !
Even if one, for some funny reason, excludes Uhuru, more interesting is the involvement of the AG in a private civil law suit between two private citizens.