Due Diligence

Nature of the Defense

Due diligence is the showing that a person charged with negligence exercised the care, attention, and foresight required by the circumstances to prevent injury. In quasi-delicts, it may operate either as a denial of the defendant's own negligence or as a statutory defense to liability for the negligent act of another.

The Civil Code recognizes quasi-delict liability when damage is caused by act or omission, there is fault or negligence, and there is no pre-existing contractual relation between the parties concerning the injury. When the defendant is sued for his own act, due diligence means that the plaintiff has failed to prove breach of the applicable standard of care. When the defendant is sued for the act of a person under his authority, due diligence is an affirmative defense that defeats the presumption of negligence in selection, supervision, custody, or control.

The defense is not a general denial of harm. It is a specific showing that the defendant took reasonable and legally adequate measures before the injury, and that the injury happened despite those measures. The inquiry is preventive, not merely reactive; prompt assistance after an accident may affect damages or good faith, but it does not by itself prove prior diligence.

Standard of Care

The ordinary benchmark is the diligence of a good father of a family, meaning the care that a reasonably prudent person would exercise in relation to the nature of the activity, the foreseeable risk, the means available to avoid the risk, and the relation between the parties. This standard is objective, flexible, and fact-sensitive.

Due diligence does not require perfection or absolute prevention of injury. It requires reasonable foresight and reasonable action against foreseeable harm. The greater the danger, the more exacting the precautions that ordinary prudence demands. A person handling vehicles, machinery, hazardous substances, minors, employees, or premises open to the public must take measures proportionate to the risk created or controlled.

Compliance with ordinary practice is relevant but not conclusive. A widespread unsafe practice does not become prudent merely because it is common. Conversely, an accident alone does not establish negligence if the defendant proves that adequate precautions were in place, properly implemented, and reasonably sufficient for the risk involved.

Burden and Proof

In direct negligence, the injured party generally bears the burden of proving the negligent act or omission, damage, and causal connection. The defendant may answer by proving that he acted with due care, that the risk was not reasonably foreseeable, that the injury was caused by another efficient cause, or that the plaintiff's evidence fails to establish breach of duty.

In vicarious quasi-delict liability, the Civil Code creates a presumption of negligence against certain persons because the wrongdoer is under their authority, custody, employment, or supervision. The responsibility ceases only when they prove that they observed all the diligence of a good father of a family to prevent damage. Thus, the burden shifts to the person made responsible to prove diligence with competent, specific, and credible evidence.

Bare assertions of diligence are insufficient. The defense must be supported by concrete facts, such as careful screening, reasonable rules, actual instruction, regular monitoring, corrective action, safe systems, proper maintenance, and enforcement suited to the activity. A written policy that is ignored in practice does not establish due diligence.

Due Diligence in Vicarious Liability

The due diligence defense is most important in cases where the law makes one person answer for the act or omission of another. The liability is not based on the fiction that the defendant personally committed the tort, but on the presumption that the defendant failed to exercise the care required by his relation to the wrongdoer.

Employers: Diligence in Selection and Supervision

An employer's defense generally has two components: diligence in selection and diligence in supervision. Both must be shown. Proof of one does not cure the absence of the other because an employer may hire a competent employee but negligently supervise him, or may maintain rules but negligently hire an unqualified or dangerous employee.

Diligence in selection requires reasonable measures before hiring or assignment. These may include verifying identity, qualifications, licenses, experience, training, physical and mental fitness for the work, employment history, safety record, and competence for the particular task. The inquiry is not limited to the employee's formal credentials; it includes whether the employer reasonably matched the employee to the risk of the job.

Diligence in supervision requires reasonable measures after hiring. It includes communicating rules, training employees, providing safe equipment, monitoring compliance, correcting unsafe conduct, investigating violations, imposing discipline, and maintaining systems that make compliance realistic. Supervision is not proven by a manual alone; it must appear that the employer made the rules known, checked observance, and enforced them.

The employee's previous clean record is useful but not decisive. A clean record may support diligence in selection, but it does not prove adequate supervision at the time of the negligent act. Likewise, the absence of prior accidents does not excuse the failure to adopt precautions required by foreseeable risk.

The defense is unavailable when the employer's own negligence is the immediate basis of liability. If the injury resulted from defective equipment, unsafe operating procedures, impossible schedules, lack of training, or deliberate disregard of known danger, the employer is directly negligent. In such a case, the issue is not merely whether the employee was carefully selected or supervised, but whether the employer itself breached a duty of care.

Acts Within the Scope of Assigned Tasks

For employer liability, the negligent employee must have been acting within assigned tasks or at least in connection with the duties entrusted to him. The phrase is not confined to acts expressly ordered by the employer. It includes acts reasonably connected with the employee's functions, even if performed in an improper, unauthorized, or negligent manner.

Due diligence may still be relevant when the employee violated instructions, but the violation does not automatically absolve the employer. The employer must show that the instruction was reasonable, known to the employee, enforced in practice, and accompanied by supervision adequate to the risk. A rule that predictably goes unenforced is weak evidence of diligence.

If the employee's act was purely personal, wholly disconnected from work, and not made possible by the employee's assigned functions in any legally meaningful way, the basis for vicarious liability may fail. In that situation, the defense may rest not only on diligence but also on the absence of the relation required for liability.

Parents, Guardians, and School Supervision

For parents and those exercising substitute parental authority, diligence is measured by the realities of custody, authority, and control. The law expects guidance, discipline, and supervision proportionate to the minor's age, maturity, prior conduct, and the danger of the activity. A very young child, a minor with known aggressive tendencies, or a child given access to dangerous objects calls for closer preventive care.

The defense does not require constant physical surveillance in every moment. It requires reasonable parental or custodial measures in light of foreseeable risk. Where the injury follows a known pattern of misconduct that the responsible adult ignored, due diligence is difficult to establish. Where the act was sudden, unforeseeable, and occurred despite reasonable instruction and supervision, the defense may apply.

For schools, teachers, and heads of establishments covered by quasi-delict rules, the focus is the period when students, pupils, or apprentices are under custody or supervision. Diligence includes adequate personnel, reasonable rules, monitoring of dangerous activities, proper equipment, discipline, and precautions appropriate to laboratories, workshops, physical education, transport, field activities, or other supervised settings.

Relation to Foreseeability and Causation

Due diligence is inseparable from foreseeability. A defendant is not negligent for failing to guard against a remote, unusual, or highly extraordinary event that ordinary prudence would not anticipate. However, once a risk is reasonably foreseeable, the defendant must take precautions that are practical and proportionate to the probability and gravity of harm.

The defendant's diligence must also relate to the cause of the injury. Measures unrelated to the risk that materialized do not defeat liability. For example, careful hiring records do not answer a claim based on failure to maintain equipment, and general classroom rules do not answer a claim based on failure to supervise a hazardous activity.

If the defendant proves due diligence but the injury was caused by the plaintiff's own negligence, a third person's independent act, or a fortuitous event, liability may be avoided because causation is lacking. If the defendant's negligence merely concurred with another cause, liability may remain, subject to rules on contributory negligence, solidary responsibility among joint tortfeasors, or reimbursement as the circumstances require.

Effect of Statutory or Regulatory Violations

Violation of a safety statute, traffic regulation, building rule, professional standard, or administrative requirement is strong evidence of negligence when the rule was designed to prevent the kind of harm that occurred. In that setting, a defendant cannot rely on generalized diligence while ignoring a specific legal duty aimed at the same risk.

Regulatory compliance, however, is not always complete due diligence. Minimum legal compliance may be insufficient when the circumstances reveal a foreseeable danger requiring additional reasonable precautions. The civil standard remains prudence under the circumstances, especially when the defendant creates, controls, or benefits from the risk.

In motor vehicle cases, doctrines protecting the public may make the registered owner or operator answerable to injured persons despite private arrangements concerning ownership, operation, or employment. Due diligence may affect rights of reimbursement or liability among responsible parties, but it cannot be used to defeat a public-facing responsibility fixed by law or settled doctrine for the protection of third persons.

Limits of the Defense

Due diligence is a complete defense only when the defendant proves that the legally required care was exercised and that no negligent act or omission attributable to him caused the damage. It is not a defense to intentional torts, bad faith, willful misconduct, or liability based on an independent statutory command that does not allow avoidance by proof of ordinary care.

The defense also fails when the defendant had actual or constructive knowledge of a dangerous condition and did not act within a reasonable time. Knowledge may arise from prior incidents, complaints, visible defects, routine inspections, the nature of the activity, or circumstances showing that the danger should have been discovered by reasonable care.

Where several persons are responsible, one defendant's diligence does not automatically exonerate another. Each person must prove the diligence required by his own relation to the injured party, the wrongdoer, or the risk. An employer, parent, school, vehicle operator, premises controller, or direct tortfeasor may face different duties even if the same injury is involved.

Practical Content of Due Diligence

The content of due diligence is proven through facts that existed before and during the incident. Courts look for systems, conduct, and enforcement, not ceremonial compliance. The strongest proof is usually a consistent pattern of preventive conduct tied to the specific risk that caused the injury.

• Before the activity: reasonable screening, planning, risk assessment, instruction, assignment of competent persons, and provision of safe tools, equipment, premises, or procedures.
• During the activity: actual supervision, monitoring, enforcement of rules, correction of unsafe acts, and control proportionate to the danger and the persons involved.
• After warning signs: prompt investigation, repair, discipline, reassignment, suspension of unsafe activity, or other measures showing that known risks were not ignored.
• After the incident: remedial conduct may corroborate the existence of a safety system, but it cannot replace proof that reasonable precautions were already in force when the injury occurred.

Ultimately, due diligence asks whether the defendant, before the damage occurred, acted as a prudent person with legal responsibility over the actor, activity, instrumentality, or risk. The defense succeeds when the injury is shown to have occurred despite reasonable prevention, and fails when the injury is traceable to a preventable lapse in selection, supervision, custody, control, maintenance, or foresight.