How do criminal defence lawyers challenge evidence in court?

When building a case in criminal court, the prosecution bears the burden of proving guilt beyond a reasonable doubt. To accomplish this, prosecutors rely heavily on evidence presented before a judge or jury. Physical evidence, witness testimony, police procedures, and more all come into play. As advocates for the accused, criminal defence lawyers carefully scrutinize all evidence. Their role entails mounting an aggressive defence on their client’s behalf, including challenging the validity and credibility of prosecution evidence. This tests the strength of the prosecution’s case and safeguards the defendant’s rights.

Attacking the chain of custody

The chain of custody establishes a paper trail tracking the collection, storage, and handling of physical evidence. Careless gaps or mistakes in this chain raise doubts about integrity or contamination. Defence lawyers grill forensic investigators and police about custody routines and any deviations. Even minor breaches become fair game to challenge admissibility. Defence attorneys also file suppression motions seeking to exclude evidence gathered through improper methods. For example, if police lacked probable cause for a car search uncovering drugs, the lawyer argues this violates constitutional rights. Or if investigators continued questioning a defendant after they requested legal counsel, statements elicited during that time face suppression challenges. Suppressing illegally gained evidence checks overzealous investigative practices.

Discrediting eyewitnesses and informants

Eyewitness misidentification plays a role in over 70% of DNA exonerations. Human memory proves unreliable. Prosecutors often downplay this fact, overstating witness confidence. To counter this, defence lawyers call expert psychological witnesses. They educate juries on established research showing how stressors impair recall accuracy during crimes. Highly suggestible police lineups also taint eyewitness testimony. Criminal informants incentivized by bargains for cooperation make them pawns for unscrupulous prosecutions. Defence counsel works aggressively to undermine informant integrity on cross-examination.

Casting doubt through expert witnesses             

Complex forensic analyses like ballistics, fingerprints, blood spatter patterns, and DNA testing rely extensively on human interpretation. Defence attorneys retain respected experts to critically evaluate procedures used by police labs or prosecution witnesses. Evidence mishandling, flawed assumptions, insufficient samples, or investigator bias all become targets. Skilled experts can scrutinize the same reports, data, or exhibits but draw starkly different conclusions. This dueling expert testimony casts doubt by exposing uncertainty surrounding the evidence.

Demanding additional discovery

Strengthening a defence also involves demanding full transparency around the prosecution’s sources. An experienced defence lawyer Brampton file discovery motions seeking additional details about physical evidence, the chain of custody, testing methods, investigator conduct, witnesses, informants, or any other relevant information. New disclosures then become fodder for fresh evidentiary challenges. Further discovery provides a crucial safeguard against concealed facts or insulation of shoddy police practices from scrutiny. All raise the barrier for prosecutors to surmount beyond a reasonable doubt. Carefully contesting questionable evidence serves truth and justice for both victims and the accused in an imperfect system with inherent human limitations. It reminds authorities of the strict adherence required to constitutional protections as a check against abuse of power. Robust defence advocacy makes rail-roading the innocent less likely while still securing punishment of the guilty upon solid proof.