The owner of a flat has given the flat to a tenant who is using it for storage i.e. commercial activities. He claims it be legal as he can get approval from majority of owners of the building.
As per your query you havent mentioned which state you belong to. Every state has different laws regarding landlord and Tenant.
However, if the building is purely a residential building then one cannot use for commercial activities and you can complain to the municipality for this illegality. Alternatively, you can seek an injunction from the civil courts to prohibit the use of such residential house for commercial purposes.
In the State of Maharashtra, using residential properties for commercial purposes is strictly prohibied under Section 30 of the Maharastra Rent Control Act, 1999 and the same can be filed a case in the small causes Courts in case of Mumbai.
If the zoning rules and the housing society management rules allow it, you can use or rent your residential property for commercial activity. However, states have different sets of rules on conversion of residential property to commercial property. Some states allow up to 30 per cent area of a house to be put to commercial use by professionals such as doctors, lawyers and chartered accountants, but others do not.In case your state allows this, it is necessary to get an approval from the housing society before conversion of residential property to commercial property. Depending on the nature of the business, it may also be necessary to obtain permission from the local municipal authority for the conversion of a flat into a commercial establishment. The civic body would levy commercial charges on the property and water and power supply, depending upon the area, the property size and the nature of business activity.
Even if he gets an approval from all the owners it will not be valid if the laws prohibit it of the State.
Reference: Section 30
Maharashtra Rent Control Act, 1999
Conversion of residential into commercial premises prohibited.
(1) A landlord shall not use or permit, to be used for a commercial purpose any premises which, on the date of the commencement of this Act, were used for a residential purpose.
(2) Any landlord who contravenes the provisions of sub-section (1) shall, on conviction, be punishable with imprisonment for a term which may extend to six months or with fine which may extend to ten thousand rupees or with both.