Here is the DE law
5308 Essential services; landlord obligation and tenant remedies.
(a) If the landlord substantially fails to provide hot water, heat, water or electricity to a tenant, or fails to remedy any condition which materially deprives a tenant of a substantial part of the benefit of the tenant's bargain in violation of the rental agreement; or in violation of a provision of this Code; or in violation of an applicable housing code and such failure continues for 48 hours or more, after the tenant gives the landlord actual or written notice of the failure, the tenant may:
(1) Upon written notice of the continuation of the problem to the landlord, immediately terminate the rental agreement; or
(2) Upon written notice to the landlord, keep 2/3 per diem rent accruing during any period when hot water, heat, water, electricity or equivalent substitute housing is not supplied. The landlord may avoid this liability by a showing of impossibility of performance.
(b) If the tenant has given the notice required under subsection (a) of this section and remains in the rental unit and the landlord still fails to provide water, hot water, heat and electricity to the rental unit as specified in the applicable city or county housing code in violation of the rental agreement, the tenant may:
(1) Upon written notice to the landlord, immediately terminate the rental agreement; or
(2) Upon notice to the landlord, procure equivalent substitute housing for as long as heat, water, hot water or electricity is not supplied, during which time the rent shall abate, and the landlord shall be liable for any additional expense incurred by the tenant, up to 1/2 of the amount of abated rent. This additional expense shall not be chargeable to the landlord if landlord is able to show impossibility of performance; or
(3) Upon written notice to the landlord, tenant may withhold 2/3 per diem rent accruing during any period when hot water, heat, water or equivalent substitute housing is not supplied.
(c) Rent withholding does not act as a bar to the subsequent recovery of damages by a tenant if those damages exceed the amount withheld.
(d) Where a landlord files an action for summary possession, claiming that a tenant has wrongfully withheld rent or deducted money from rent under this section and the court so finds, the landlord shall be entitled to receive from the tenant either possession of the premises or an amount of money equal to the amount wrongfully withheld ("damages") or, if the court finds the tenant acted in bad faith, an amount of money equal to double the amount wrongfully withheld ("double damages"). In the event the court awards damages or double damages and court costs excluding attorneys' fees, then the court shall issue an order requiring such damages or double damages to be paid by the tenant to the landlord within 10 days from the date of the court's judgment. If such damages are not paid in accordance with the court's order, the judgment for damages or double damages, together with court costs, shall become a judgment for the amount withheld, plus summary possession, without further notice to the tenant.