Also known as: reasonable degrees of certainty · reasonable medical certainty · reasonable scientific certainty
Written by attorneys · grounded in primary & secondary sources — see below
A standard of evidentiary proof that requires a tenant claiming lost business profits to present evidence sufficient to remove the calculation from the realm of speculation. The standard is satisfied by reliable data such as prior sales history, pre-lease commitments, or expert projections when the lease contemplates business use.
Lena leased a storefront from Martin for a boutique retail launch timed to the city's annual music festival. Martin failed to complete required accessibility work, blocking city approval and preventing the opening. Lena introduced her existing online store sales data to project festival revenue. The court permitted recovery of the lost profits because the evidence met the reasonable degree of certainty standard.
Paula leased commercial space from Quinn to open a restaurant. Quinn's failure to repair the HVAC system forced closure during the first holiday season. Paula offered tax returns from her prior catering business and an expert's market analysis to quantify lost profits. The court found the evidence satisfied the reasonable degree of certainty standard and allowed recovery.
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Sam leased a mall location from Tara for a new store branch. Tara breached by leasing adjacent space to a direct competitor in violation of the exclusivity clause. Sam proved lost profits to a reasonable degree of certainty with historical sales data from other branches and demographic studies the parties had reviewed before signing. The court awarded damages on that basis.
Reliable data such as prior sales figures, pre-lease commitments, market comparables, or expert testimony suffice when they remove the calculation from speculation. Courts accept such evidence even for new businesses if it provides a rational basis for the projection.
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No. The standard requires only a reasonable basis that eliminates speculation, not exact numerical certainty. Evidence such as industry reports and expert projections meets the threshold when it supports a credible estimate.
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No. The landlord's default must be a substantial contributing cause shown with reasonable certainty. Alternative explanations raised by the landlord create factual disputes but do not automatically defeat recovery when the tenant supplies concrete evidence tying the loss to the breach.
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Foreseeability is a separate element. The tenant must still prove the amount of loss to a reasonable degree of certainty even when the type of harm was foreseeable at contracting.
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…a bite. Defendant reasons that his opinion was inadmissible because (1) he couched his opinion in terms of mere possibility, not reasonable medical certainty; (2) given the prosecution's theory and the judge's ruling that impossibility was not a defense, the doctor's opinion was irrelevant and inflammatory; and (3) the doctor failed to cite a…