“ The general requirement that losses be deducted in the year in which they are sustained calls for a practical, not a legal, test.'
The standard for determining the year for deduction of a loss is thus a flexible, practical one, varying according to the circumstances of each case. The taxpayer's attitude and conduct are not to be ignored, but to codify them as the decisive factor in every case is to surround the clear language of § 23 (e) and the Treasury interpretations with an atmosphere of unreality and to impose grave obstacles to efficient tax administration. ”

“ But the question of whether particular corporate stock did or did not become worthless during a given taxable year is purely a question of fact to be determined in the first instance by the Tax Court, the basic fact-finding and inference-making body. The circumstance that the facts in a particular case may be stipulated or undisputed does not make this issue any less factual in nature. The Tax Court is entitled to draw whatever inferences and conclusions it deems reasonable from such facts. ”

“ The mere fact that the defendants were financially responsible does not necessarily inject any recognizable value into the suit from the stockholders' viewpoint. Hence it was reasonable to conclude that all value had departed from the stock prior to 1937 and that there was nothing left except a claim for damages against third parties for destruction of that value.
The taxpayer points to the consequences of error and other difficulties confronting one who in good faith tries to choose the proper year in which to claim a deduction. ”