The Phenolphthalein Test and Its Evidentiary Value

Almost every trap case in India is built on the same chemistry. The currency notes to be paid are smeared with phenolphthalein powder, which is colourless; if the accused handles them, traces transfer to his hands or clothing; his hands are then washed in a solution of sodium carbonate, which turns pink in the presence of the powder. The test is simple, cheap and visually dramatic, and it is also frequently over-read. It proves that the accused came into contact with the treated notes. It does not prove that he demanded them, that he accepted them as an undue advantage, or that the money was connected with any official act.

1. How the Test Is Conducted

1. The pre-trap panchnama. The complainant produces the currency notes; their numbers are recorded; phenolphthalein powder is applied; a demonstration wash is performed in the presence of the panch witnesses so that they can depose to the reaction; the notes are handed back to the complainant with instructions; and the shadow witness is directed to accompany him and to give a signal.
2. The trap. The complainant pays on demand; the shadow witness overhears the exchange; the signal is given and the team intervenes.
3. The recovery. The notes are recovered from the accused, his person, his table drawer or another place, and the numbers are compared with those recorded.
4. The wash. The fingers of both hands are dipped separately in a fresh solution of sodium carbonate; where the notes were placed in a pocket or in a bag, that article is also washed. The solutions are collected in separate bottles, sealed and labelled.
5. The post-trap panchnama, recording each of these steps, and the forwarding of the sealed bottles for chemical examination.

2. What the Test Proves

A positive result establishes contact with the treated notes, and nothing more. That is a useful fact, because it excludes the claim that the accused never touched the money and it corroborates the evidence of recovery, but it is corroborative rather than substantive. The chain of inference runs from contact to handling, from handling to receipt, and from receipt to acceptance as an undue advantage, and each step requires evidence beyond the colour change.

3. The Defences Commonly Raised

• The notes were thrust into my hand or my pocket. A common defence and one the prosecution must exclude by the evidence of the shadow witness and by the surrounding circumstances; the wash cannot distinguish between a voluntary receipt and a forced one.
• The money was paid for a lawful reason. Repayment of a loan, a fee payable to the office, a subscription or a payment for goods. Once acceptance is proved the burden of establishing such an explanation lies on the accused, but it is discharged on the preponderance of probabilities.
• Contact without receipt. Where the accused pushed the money away, counted it and returned it, or touched it while remonstrating, the wash is positive and the acceptance is absent.
• Transfer from another source. Phenolphthalein is in common use; contact with a treated surface other than the notes, including contact with the complainant's hand, can produce the reaction.

4. Defects That Weaken the Evidence

1. No independent panch witness, or an official witness only. The panchas are frequently government servants summoned from a nearby office, and a panch who is shown to be a habitual witness for the agency reduces the weight of the evidence considerably.
2. No demonstration wash before the trap. Without it the witnesses cannot depose that they understood what the reaction signified.
3. The wash solutions not sealed, labelled or separately preserved, or the bottles not sent for chemical examination, or sent after unexplained delay, which opens the chain of custody to attack.
4. Failure to wash the pocket or the article in which the notes were said to have been kept, where the prosecution case is that they were placed there.
5. The numbers of the notes not recorded, or a discrepancy between the notes recorded and those recovered.
6. The shadow witness not in a position to hear, which is the defect that most often destroys the proof of demand, since the shadow witness exists precisely to depose to it.

5. How the Evidence Should Be Presented and Tested

For the prosecution, the test is one link in a chain that begins with the complaint and the verification of the demand and ends with the recovery and the wash. The chain is only as strong as the proof of demand, so the shadow witness and the verification are more important than the chemistry. For the defence, the attack is directed at the two ends rather than at the middle: whether a demand was made and proved, and whether the receipt was voluntary and connected with an official act. Attacking the chemistry alone rarely succeeds, because a positive wash is difficult to explain away; attacking the inference drawn from it frequently does.

6. Related Topics and Provisions