The police departments of the respective counties may establish and implement intoxicant control roadblock programs in accordance with the minimum standards and guidelines provided in § 291E-20. The chief of police in any county establishing an intoxicant control roadblock program pursuant to this section shall specify the procedures to be followed in carrying out the program in rules adopted under chapter 91; provided that the procedures shall be in conformity with and not more intrusive than the standards and guidelines described in § 291E-20. In the case of internal police standards that do not fall within the definition of “rule” under § 91-1, failure to comply scrupulously with the internal police procedures shall not invalidate a roadblock that otherwise meets the minimum statutory criteria provided in § 291E-20.