Given that they were in uniform, carrying out other police duties contemporaneously, slashing a tire without any basis for doing so would constitute a seizure of property without probable cause, in violation of the 4th Amendment (as incorporated against state and local governments via the 14th Amendment's due process clause). This would provide a basis for a lawsuit under 42 U.S.C. § 1983 against the officer in question for an intentional violation of a constitutional right.

While some violations of constitutional rights are not "well-established" constitutional rights for which qualified immunity would provide protection, the duty to refrain from intentionally damaging a person's property without having any justification for doing so, would likely not be barred by qualified immunity and would be considered a "well-established" constitutional right.

Prevailing in a 1983 lawsuit would result in an award of compensatory damages (possibly including non-economic damages), at least, plus attorneys fees and out of pocket litigation costs. I don't recall if punitive damages would be available in this context.

In the alternative, if the person sued argued that they were not acting under color of state law despite wearing a uniform and being on duty as a police officer involved in some sort of traffic stop, the victim could sue the person who slashed their tires for "conversion" and seek money damages under that common law tort. A conversion action would result in an award of economic, non-economic, and punitive damages, and the out of pocket costs of litigation, but not attorney fees.

Typically, 1983 actions are filed in federal court since they arise from a federal cause of action.

The police department that employed the officer who slashed the tire would probably not have liability as one would have to show that the department had a policy of slashing people's tires for no reason, that it almost surely did not have.

Given that they were in uniform, carrying out other police duties contemporaneously, slashing a tire without any basis for doing so would constitute a seizure of property without probable cause, in violation of the 4th Amendment (as incorporated against state and local governments via the 14th Amendment's due process clause). This would provide a basis for a lawsuit under 42 U.S.C. § 1983 against the officer in question for an intentional violation of a constitutional right.

While some violations of constitutional rights are not "well-established" constitutional rights for which qualified immunity would provide protection, the duty to refrain from intentionally damaging a person's property without having any justification for doing so, would likely not be barred by qualified immunity and would be considered a "well-established" constitutional right.

Prevailing in a 1983 lawsuit would result in an award of compensatory damages (possibly including non-economic damages), at least, plus attorneys fees and out of pocket litigation costs. I don't recall if punitive damages would be available in this context.

In the alternative, if the person sued argued that they were not acting under color of state law despite wearing a uniform and being on duty as a police officer involved in some sort of traffic stop, the victim could sue the person who slashed their tires for "conversion" and seek money damages under that common law tort. A conversion action would result in an award of economic, non-economic, and punitive damages, and the out of pocket costs of litigation, but not attorney fees. But, in context, an argument that this action was not under color of state law would be a hard sell.

Typically, 1983 actions are filed in federal court since they arise from a federal cause of action.

The police department that employed the officer who slashed the tire would probably not have liability as one would have to show that the department had a policy of slashing people's tires for no reason, that it almost surely did not have.

Another defense of the police officer would be to concoct a plausible justification for the action. For example, if the officer slashing the tire testified that an informant told him that there were warrants out for the arrest of a rear seat passenger who was about to get away.