8.3 Specimens Used as Legal Evidence

AMT's last phlebotomy practice item is to describe and follow the criteria for specimens and test results that will be used as legal evidence (II.3.B.14). This is not a courtroom-procedure chapter. CMLA tests whether you collect and document so the specimen could be used as evidence: identity of the donor, integrity of the container, and an unbroken chain of custody (COC). You do not argue objections, authenticate exhibits for a judge, or invent a testimony script. You follow the facility legal-collection SOP, the workplace-testing protocol, or the law-enforcement kit in your hand.

Quick Answer: Photo ID, witnessed or secured collection as the protocol requires, tamper-evident seals, a chain-of-custody form that records every handoff, and no unobserved gaps. Legal blood alcohol is often a gray-top fluoride/oxalate tube; if the facility forbids alcohol skin prep, use iodine or soap as SOP states. Workplace drug screens use the kit, the seal, and the form—not a leftover chemistry cup.

What "legal evidence" means in the laboratory

A legal (forensic, evidential, medicolegal) specimen may be used in employment actions, criminal or civil proceedings, child-protective cases, or other official determinations. Ordinary clinical tubes are medical specimens. They have PRE01 identification, but they do not automatically have a chain of custody. If someone later asks whether a urine cup could have been switched, a clinical label with a name and a time may not answer. A legal collection is designed so you can say who the donor was, what was collected, when, who handled it, and that the container was sealed against tampering.

Results inherit the specimen. A perfect confirmatory method (GC/MS or LC/MS from Chapter 5) on a cup that sat unsealed in a break room is still a failed legal collection. Confirmation does not repair a broken chain.

Chain of custody

Chain of custody is the paper or electronic record of every transfer of the specimen from collection through reporting. Typical entries include donor identifiers and ID-document type; date, time, and location of collection; tests requested; collector name and signature; specimen type, unique specimen ID, and seal numbers; each subsequent custodian (accessioner, courier, receiving tech) with date and time; and storage locations when the specimen is not in hand.

No unobserved gaps means the sealed specimen is not left on a counter "for a minute" while you answer the phone, not left in an unlocked basket for a courier who might come, and not stored in a shared fridge without a log. If you cannot account for a period, the chain is broken. Stay with the specimen or lock it in designated COC storage, then document the handoff. The COC form travels with the specimen or in the required pouch. Do not file it in a drawer because the analyzer already has a barcode.

Identity, witnessing, and tamper-evident seals

Legal collections raise the identification bar:

• Photo ID (driver's license, state ID, passport, or the ID the protocol names). Match the photo, the name, and the signature to the donor in front of you. A coworker saying "that's him" is not photo ID.
• Some protocols add a signature comparison or a witnessed signature on the COC.
• Witnessed collection is required for many workplace urine drug screens and some forensic urine collections: a same-sex observer or a monitored bathroom as the protocol specifies. Blood collections for alcohol or drugs are not left unattended after labeling and sealing; extra witnesses follow the kit, not your preference.

After collection, apply a tamper-evident seal across the container cap so opening it tears the seal. The donor typically initials the seal. Record seal numbers on the COC. Do not reopen a sealed legal specimen to "top off" volume or to pour an in-house waived cup. If the seal is broken on arrival, that is a documented integrity failure, not a labeling inconvenience.

Legal blood alcohol

Evidential blood alcohol collections commonly use a gray-top tube with sodium fluoride (glycolysis inhibitor / preservative) and potassium oxalate (anticoagulant). Fluoride helps keep ethanol from disappearing through glycolysis and limits some microbial fermentation. Do not substitute an SST "because chemistry can run alcohol" unless the legal kit and the receiving laboratory name that tube.

Skin prep is the classic CMLA trap. Many forensic and facility procedures forbid alcohol-containing antiseptics so nobody can claim the ethanol on the skin contaminated the tube. In those facilities, cleanse with povidone-iodine, chlorhexidine if allowed, or soap and water as the SOP lists, then dry. If a stem says the facility forbids alcohol prep, do not argue that 70% isopropanol evaporates. If a stem gives a protocol that allows alcohol that has fully dried, follow that protocol. The exam point is SOP over habit, not a debate about whether residual alcohol actually raises blood ethanol.

Do not use leftover blood from a green-top you already spun. Do not pop a gray-top to share with hematology. Fill, mix by inversion, seal, and hand off on the chain.

Workplace drug-screen collections

Federally regulated (for example, Department of Transportation) and many employer collections follow a kit:

• Secure bathroom: bluing in the toilet and restricted water sources as the protocol requires
• Donor removes coats and bags as specified
• Temperature strip on urine within the allowed range and time
• Split specimens (Bottle A / Bottle B) when the program uses splits
• Tamper-evident seals, donor initials, and completion of the custody and control form
• Shipment to a certified laboratory; an in-house waived cup is not a substitute for a regulated confirmation pathway

If the donor cannot produce urine, follow shy-bladder rules in the protocol; do not send faucet water. If the specimen is out of temperature range or shows tampering, document and follow recollection or invalid rules—do not quietly pour it out and try again off-book.

Blood or oral-fluid workplace tests, when used, still need ID, seals, and a chain. A purple-top leftover from a CBC is not a forensic toxicology kit.

Clinical versus legal handling — stay in assistant scope

You may collect and document. You do not decide guilt, impairment, or whether a result "will hold up in court." You do not coach a donor on how to beat a test. You do not discuss results in a hallway (HIPAA still applies; Chapter 16).

In practice

Employee health presents a kit for blood alcohol and a urine drug screen. You verify photo ID, open the kit in view, use the gray-top, cleanse with the non-alcohol antiseptic your SOP names, fill, invert, seal, and complete every COC line. Urine is collected under the witnessing rules on the form, sealed, temperature-checked, and placed in the kit pouch. You lock the kit or hand it to the listed courier and get a signature. You do not leave it at the front desk.

Exam traps

• A clinical label is not a chain of custody.
• Gray-top for evidential alcohol, not "any chemistry tube."
• Alcohol skin prep is forbidden when the facility says it is.
• Breaking a seal to aliquot for waived testing destroys the legal specimen.
• Unobserved time on a counter is a gap, even if you "knew nobody would touch it."

When a stem says the result will be used as evidence, slow down: ID, seal, form, and custody—not a faster draw.