38 CFR § 3.318 - Presumptive service connection for amyotrophic lateral sclerosis.
(a) Except as provided in paragraph (b) of this section, the development of amyotrophic lateral sclerosis manifested at any time after discharge or release from active military, naval, or air service is sufficient to establish service connection for that disease.
(b) Service connection will not be established under this section:
(1) If there is affirmative evidence that amyotrophic lateral sclerosis was not incurred during or aggravated by active military, naval, or air service;
(3) If the veteran did not have active, continuous service of 90 days or more.