law: The Indian Succession Act, 1925
  Chapter II- Of Wills and Codicils
  59. Person capable of making wills.-
  Every person of sound mind not being a minor may dispose of his property by will.
  Explanation 1.-A married woman may dispose by will of any property which she could alienate by her own act during her life.
  Explanation 2.-Persons who are deaf or dumb or blind are not thereby incapacitated for making a will if they are able to know what they do by it.
  Explanation 3.-A person who is ordinarily insane may make a will during interval in which he is of sound mind.
  Explanation 4.-No person can make a will while he is in such a state of mind, whether arising from intoxication or from illness or from any other cause, that he does not know what he is doing.
  Illustrations
  (i) A can perceive what is going on in his immediate neighbourhood, and can answer familiar questions, but has not a competent understanding as to the nature of his property, or the persons who are of kindred to him, or in whose favour it would be proper that he should make his will. A cannot make a valid will.
  (ii) A executes an instrument purporting to be his will, but he does not understand the nature of the instrument, nor the effect of its provisions. This instrument is not a valid will.
  (iii) A, being very feeble and debilitated, but capable of exercising a judgment as to the proper mode of disposing of his property, makes a will. This is a valid will.
  60. Testamentary guardian.-
  A father, whatever his age may be, may by will appoint a guardian or guardians for his child during minority.
  61. Will obtained by fraud, coercion orimportunity.-
  A will or any part of a will, the making of which has been caused by fraud or coercion, or by such importunity as takes away the free agency of the testator, is void.
  Illustrations
  (i) A, falsely and knowingly represents to the testator, that the testator's only child is dead, or that he has done some undutiful act and thereby induces the. testator to make a will in his, A's favour; such will has been obtained by fraud, and is
  (ii) A, by fraud and deception, prevails upon the testator to bequeath a legacy to him. The bequest is void.
  (iii) A, being a prisoner by lawful authority, makes his will. The will is not invalid by reason of the imprisonment.
  (iv) A threatens to shoot B, or to burn his house or to cause him to be arrested on a criminal charge, unless he makes a bequest in favour of C. B, in consequence, makes a bequest in favour of C. The bequest is void, the making of it having been caused by coercion.
  (v) A, being of sufficient intellect, if undistrubed by the influence of others, to make a will yet being so much under the control of B that he is not a free agent, makes a will, dictated by B. It appears that he would not have executed the will but for fear of B. The will is invalid.
  (vi) A, being in so feeble a state of health as to be unable to resist importunity, is pressed by B to make a will of a certain purport and does so merely to purchase peace and in submission to B. The will is invalid.
  (vii) A being in such a state of health as to be capable of exercising his own judgment and volition, B uses urgent intercession and persuasion with him to induce him to make a will of a certain purport. A, in consequence of the intercession and persuasion, but in the free exercise of his judgment and volition makes his will in the manner recommended by B. The will is not redered invalid by the intercession and persuasion of B.
  (viii) A, with a view to obaining a legacy from B, pays him attention and flatters him and thereby produces in him a capricious partiality to A. B, in consequence of such attention and flattery, makes his will, by which he leaves a legacy to A. The bequest is not rendered invalid by the attention and flattery of A.
  62. Will may be revoked or altered.-
  A will is liable to be revoked or altered by the maker of it at any time when he is competent to dispose of his property by will.