POLICE POWER 23 



that a man fully equipped according to modern 

 standards would gain admission to practice where 

 he chose. The medical profession is overcrowded, 

 and the consequent difficulty in obtaining recip- 

 rocal licenses has resulted in schemes for getting 

 around the present condition by making all state 

 boards recognize the authority of some national 

 board. This condition may arise in the veterinary 

 profession. According to past decisions such an 

 arrangement is constitutionally impossible. 



13. Alienum Non Laedat. There is an old prin- 

 ciple of the common law which is very powerful, 

 even at the present time in spite of its age, which 

 is known legally as alienum tuum non laedat; this 

 means that a person may so enjoy the use of his 

 own property that it shall work no injury to an- 

 other. This is one of the principles of the police 

 power which plays an important part in laws, 

 ordinances, and executive action, as well as in 

 court trials. A man may own a lot in town upon 

 which he seeks to build a livery stable, or to erect 

 a veterinary hospital. He may have actually 

 spent a large amount of money in erecting the 

 building and putting in the equipment. There 

 may be no statute or ordinance prohibiting such 

 use of the building, and he may have had the ap- 

 proval of his plans by the city building inspectors. 

 All these things may be true, and still before he 

 attempts to use his building for the purpose in- 

 tended he may be checked by an injunction. The 

 Massachusetts court held that it is not necessary 

 for the board of health to wait until a nuisance 

 has actually occurred before getting an injunction 



