Zach Marshall’s Method for Reviewing Multi-Vehicle Crashes
Multi-vehicle crashes are some of the most misunderstood events in both DUI and PI litigation.
Attorneys often receive a police report that simplifies a three-car, four-car, or chain-reaction collision into a single “at-fault driver,” even when the physics point in a completely different direction.
That’s where my work comes in.
As a DUI and collision-analysis consultant, I (Zachary Marshall) break these events down into a sequence of movements so attorneys can see what actually happened — not what an officer assumed, not what an insurer summarized, but the true mechanics of the crash.
Here’s how I approach multi-vehicle collisions step by step.
1. Start With the Sequence, Not the Conclusion
Every multi-vehicle crash has a timeline — even if no one documents it cleanly.
My first priority is to reconstruct:
• the initial trigger
• order of impacts
• spacing and timing between vehicles
• direction and speed of each car
• lane positioning and drift patterns
When attorneys see this sequence mapped correctly, the true causal event becomes clear — and it’s often not the vehicle the police blamed.
I’ve seen countless cases where the collision attributed to one driver (including clients facing DUI allegations) was actually started by a completely different vehicle upstream in the chain.
2. Identify the True “Initiating Vehicle”
In single-vehicle crashes, causation is often simple.
In multi-vehicle crashes, the initiating force can be subtle.
When I, Zach Marshall, review these cases, I analyze:
• which vehicle lost control first
• which driver made the first significant input (steer, brake, lane change)
• whether another vehicle’s sudden stop or merge triggered the chain
• whether impact timing matches the stated narrative
• whether the visible damage patterns support the assigned fault
This is where attorneys often gain the most leverage — because once the initiating action is identified, liability usually shifts.
3. Analyze Speed, Distance, and Reaction Time
Reaction time is one of the most misunderstood aspects of multi-vehicle crashes.
Even a well-trained, fully attentive driver cannot avoid:
• sudden stops with minimal gap
• abrupt lane incursions
• unexpected braking in heavy traffic
• vehicles ricocheting into their path
When I reconstruct these collisions, I calculate:
• available stopping distance
• expected reaction time
• opportunity (or no opportunity) to evade
• whether the driver had any realistic chance to avoid impact
This is particularly important in cases where one driver — sometimes the DUI-accused driver — had no physical abilityto avoid the collision despite impairment allegations.
4. Use Damage Patterns to Confirm (or Contradict) the Narrative
Damage tells the truth.
I look at:
• crush depth
• bumper alignment
• angular impact signatures
• intrusion patterns
• vehicle rotation
• post-impact trajectories
Multi-vehicle crashes create “cascading” damage.
When analyzed correctly, these patterns reveal the real flow of the event.
Many attorneys who bring me (Zachary Marshall) onto these cases are surprised how often the physical evidence contradicts the written report.
5. Separate Causation From Legal Fault
This is where multi-vehicle cases get tangled.
Causation = what physically started the crash.
Fault = how each driver behaved under the circumstances.
A driver may:
• be impaired but not cause the crash
• be inattentive but not be the initiating force
• be struck due to someone else’s unsafe lane change
• be blamed even though their vehicle had no opportunity to evade
I emphasize this distinction in every multi-vehicle evaluation because it’s often the key to resolving both DUI and PI cases favorably.
Attorneys consistently tell me that this separation is one of the most valuable parts of my work.
6. Provide a Clean, Defensible Breakdown for Litigation
A multi-vehicle review by Zachary Marshall gives attorneys:
• a technical sequence of events
• clear identification of the initiating vehicle
• analysis of reaction time and avoidability
• an evidence-backed critique of the police narrative
• a stronger foundation for negotiation and trial strategy
My goal is simple:
Give attorneys a clear, physics-based explanation they can use immediately — without wading through scattered, inconsistent reports.
Why Attorneys Bring Zachary Marshall Into Multi-Vehicle Cases
Because these cases are high-stakes.
The wrong narrative can tank a PI claim or intensify a DUI allegation.
A correct reconstruction — especially one grounded in physics rather than assumption — often changes the entire posture of a case.
Attorneys work with me because:
• I translate complex mechanics into courtroom-ready explanations
• I identify the true causal chain
• I help separate impairment allegations from actual crash dynamics
• My evaluations strengthen both negotiations and trial prep
• My analysis often reveals leverage they didn’t realize they had
In other words, multi-vehicle crashes aren’t just “pileups.”
They’re solvable puzzles — and solving them is part of what I do best.
