The article is about exclusionary rules in criminal law, which are rules that dictate leaving evidence out of a trial if that evidence has been obtained in a breach of the defendant's constitutional rights. Madden, the author, states that the current exclusionary laws are too complex, and he proposes a simple and flexible principle-based rule instead.
The author first considers the rationale for exclusionary rules, including deterrence of future police civil rights infractions; condonation (meaning that the state condones these infractions if it does not exclude evidence); compensation (meaning the victim of civil rights infractions should be compensated for the wrongs committed against him/her); and vindication (meaning that the law provides remedies if constitutional rights have been breached). However, the author feels that exclusionary rules can be explained in "abstract and philosophical terms" (page 452). The author also speaks about reasons why exclusionary rules should not be used, including the protection of public safety.
The author then proposes the following principle-based rule:
"Evidence obtained through a rights breach should be excluded whenever exclusion will advance objectives of deterrence, dissociation, vindication or compensation, and the gains that exclusion will bring in one or more of these areas are larger than any social costs of exclusion in terms of public safety, efficiency, proportionality, or epistemic sacrifices or risks" (page 488).
In other words, evidence gathered while committing a breach of someone's civil rights should be excluded if exclusion furthers the goals of deterrence, dissociation, compensation, and vindication and if these gains outweigh the negative effect that excluding evidence would have on public safety and related issues.