PAPER IV
Semester IX(A)
B.A.LL.B. (Hons.)- Five Year Integrated Course
Faculty of Law
University of Allahabad
Nandini Raizada
Assistant Professor,
Department of Law,
C.M.P. Degree College, Prayagraj.
Lecture Iv
Unit-I: Introduction to Forensic Science
PRINCIPLES OF FORENSIC SCIENCE (Continued…)
4. LAW OF COMPARISON
Only likes can be compared
It is the principle of comparison. It emphasizes the necessity for providing like
samples and specimens for comparisons with questioned items. Like hair recovered
from a negro can be compared with a negro only.
5. LAW OF ANALYSIS
The analysis can be no better than the sample analysed.
Improper sampling and contamination render the best analysis useless. The principle
emphasizes the necessity of correct sampling and correct packing for effective and
worthwhile results.
6. LAW OF PROBABILITY
Probability determines the chances of occurrence of a particular event in a particular
way out of a number of ways in which the event can take place or failed to take place
with equal facility or identification, definite or indefinite, are made consciously or
unconsciously, on the basis of probability.
If P represents probability, and NS represents the number of ways in which the event
can successfully occur ( with equal facility) and N F represents the number of ways in
which it can fail (with equal facility). The probability of success is given as:
PS= NS/( NS+ NF)
*This content is only meant for online teaching purpose. No copyright is claimed by the author.
PAPER IV
Semester IX(A)
B.A.LL.B. (Hons.)- Five Year Integrated Course
Faculty of Law
University of Allahabad
Nandini Raizada
Assistant Professor,
Department of Law,
C.M.P. Degree College, Prayagraj.
If the event consists of two or more occurrences which can take place independently,
the net probability
Pt= P1 X P2 X………..PN
7. LIKELIHOOD RATIO
In calculating the likelihood ratio, the probabilities of both of chances of occurrence
and non- occurrence are calculated. The ratio of the two gives the likelihood ratio.
8. FACTS DO NOT LIE, MEN CAN AND DO
The oral testimony of the witnesses is modified by auto suggestion, external
influence, suggestions, descriptions and opinions of others, conscious and
unconscious bias and rationalization. Oral evidence, therefore, is coloured whereas
material evidence is free from these infirmities.
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*This content is only meant for online teaching purpose. No copyright is claimed by the author.
