Seems the issue are the bank charges levied between November 1989 when the law was enacted and May 2006 when the Legal Notice No. 34 of 2006 was enacted.

The banks that would be most affected if this case was to be ruled in favour of the depositors would be the two dorminant banks of that era ie Barclays and Stanchart (the case in court involves stanchart).

But the penalty for contravening the said provisions of this Act are also stipulated: Section 49 prescribes penalty fines for any
contravention of the Banking Act as a maximum of Khs. 100,000 for a body corporate and a
maximum of Kshs.50,000 or a two year imprisonment or to both for every officer of
the institution who cannot justify the contravention.
Section 55 of the Act gives the minister power to prescribe penalties to be paid by
institutions which fail or refuse to comply with any directions by the Central Bank
under the Act.

Lawyers in the house can shed some more light but the financial sector seems adept at protecting its interests.....