The Police Power extends to " the protection of the lives, limbs, health, comfort and quiet of all persons and the protection of all property within the state."1 An exact definition, though often attempted, is impossible.2 From the nature of the police power it is clear that the legislature can neither contract away its police power nor authorize any agency of the State or any public corporation so to do.3 Accordingly, since this clause of the Constitution gives no additional validity to invalid contracts,4 contracts which tend to restrict the police power unduly may be abrogated by subsequent legislation. Such legislation is not an impairment of the obligation of contracts.5 Thus no contract can prevent a state from subsequently exercising its powers to suppress lotteries,6 or to change the place for holding court,7 or to impose new requirements for the practice of medicine, if reasonable,8 or to impose a license tax on those practising a given profession, such as lawyers,9 or to require a safe viaduct over railroad tracks at the crossing of an important street in a large city,10 or to require a viaduct to be repaired,11 or to require a railway to keep in order all bridges necessary, to enable public roads to cross the railway,12 or to maintain and repair crossings over its roads,13 or to require gates at grade crossings,14 or to restrain the right of a railroad company to lay tracks across a highway,15 or to prevent a street railroad from tearing up streets without permission from the aldermen,16 or to require a street railway company to clean,17 or to sprinkle,18 the space between its tracks, or to require proper fishways in dams,19 or to require street cars to be so constructed as to give reasonable protection to their employes,20 or to restrain the sale of intoxicating liquors.21 Thus the charter of an insurance company does not prevent the state from passing subsequent statutes to require annual statements of the condition of the company to be filed,22 or to make an insurance company liable on policies thereafter issued, for the face of the policy in case of total loss,23 or to make a railroad company liable for damage caused by fire from its locomotives,24 or to impose liability on the initial carrier where it is alleged that goods were injured while in the custody of a connecting carrier, unless within thirty days after application it traces the damaged freight, and gives written information to the applicant when, where, how and by whom such freight was damaged, and the names of the parties by whom the truth of such facts can be established.25 An insurance company which was entitled when its policies issued, to be subrogated to the claims of the insured against the railroad company for the full value of the property insured, cannot complain because a subsequent statute restricts the liability of the railroad to the difference between the value of the property destroyed and the amount of insurance thereon, though such restriction defeats the right of subrogation.26

14 Duluth, etc., R. R. v. St. Louis County, 179 U. S. 302; Stearns v. Minnesota, 179 U. S. 223; Smith v. Ry., 64 Fed. 272; Bryan v. Board of Education, 90 Ky. 322; 13 S. W. 276.

13 Duluth, etc., R. R. v. St. Louis County, 179 U. S. 302; (reversing State v. Duluth, etc., R. R., 77 Minn. 433; sub nom. St. Louis County v. R. R., 80 N. W. 626) ; Stearns v. Minnesota, 179 U. S. 223; reversing State v. Stearns, 72 Minn. 200; 75 N. W. 210.

16 Greenwood v. Freight Co., 105 U. S. 13; Shields v. Ohio, 95 U. S. 319; Buffalo, etc., Ry. v. Dudley, 14 N. Y. 336.

17 Leep v. Ry., 58 Ark. 407; 41 Am. St. Rep. 109; 23 L. R. A. 264; 25 S. W. 75.

1 Ingram v. Colgan, 106 Cal. 113;

46 Am. St. Rep. 221; 28 L. R. A. 187; 38 Pac. 315; 39 Pac. 437.

2 Stone v. Mississippi, 101 U. S. 814. " The police power of the state, so far has not received a full and complete definition. It may be said, however, to be the right of the state, or state functionary, to prescribe regulations for the good order, peace, health, protection, comfort, convenience and morals of the community which do not encroach on a like power vested in Congress by the Federal Constitution or which do not violate any of the provisions of the organic law. Of this power it may be said that it is known when and where it begins but not when and where it terminates." Champer v. Greencastle, 138 Ind. 339, 351; 46 Am. St. Rep. 390; 24 L. R. A. 768; 35 N. E. 14.

3 "No one legislature can curtail the power of its successors to make such laws as they deem proper in matters of police." Metropolitan Board of Excise v. Barrie, 34 N. Y. 657, 668; quoted in Stone v. Mississippi, 101 U. S. 814, 888; so Boyd v. Alabama, 94 U. S. 645.

4 See Sec. 1751.

5 Chicago, etc., Ry. v. Nebraska, 170 U. S. 57; Douglass v. Kentucky, 168 U. S. 488; Swartz v. Lake County, 158 Ind. 141; 63 N. E. 31; State v. Meek, 112 la. 338; 84 Am. St. Rep. 342; 51 L. R. A. 414; 84 N. W. 3; Baker v. Lexington (Ky.), 53 S. W. 16; State v. Coleman, 64 O. S. 377; 55 L. R. A. 105; 60 N. E. 568; Knoxville v. Bird, 12 Lea (Tenn.) 121; 47 Am. Rep. 326.

6 Douglass v. Kentucky, 168 U. S. 488; (affirming Commonwealth v. Douglass, 100 Ky. 116; 66 Am. St. Rep. 328; 24 S. W. 233) ; Stone v. Mississippi, 101 U. S. 814.

7 Swartz v. Lake County, 158 Ind. 141; 63 N. E. 31.

8 State v. Coleman, 64 O. S. 377; 55 L. R. A. 105; 60 N. E. 568.

9 Baker v. Lexington (Ky.), 53 S. W. 16.

10 Chicago, etc., Ry. v. Nebraska, 170 U. S. 57.

11 Chicago, etc., Ry. v. State. 47 Neb. 549; 53 Am. St. Rep. 557; 41 L. R. A. 481; 66 N. W. 624.

12 Illinois Central Ry. v. Copiah County, 81 Miss. 685; 33 So. 502.

13 (Town of) Clarendon v. R. R., 75 Vt. 6; 52 Atl. 1057.

14 (Inhabitants of) Palmyra Township v. Ry., 63 N. J. Eq. 799; 52 Atl. 1132; affirming 62 N. J. Eq. 601; 50 Atl. 369.

15 Pittsburgh, etc., Ry. v. Chicago, 159 111. 369; 42 N. E. 781.

16 City of Westport v. Mulhol-land, 159 Mo. 86; 53 L. R. A. 442; 60 S. W. 77.

17 (City of) Chicago v. Traction Co., 199 111. 259; 59 L. R. A. 666; 65 N. E. 243.

18 City, etc., Ry. v. Mayor of City of Savannah, 77 Ga. 731; 4 Am. St. Rep. 106; State v. R. R., 50 La. Ann. 1189;' 56 L. R. A. 287; 24 So. 265.

19 State v. Meek, 112 la. 338; 84 Am. St. Rep. 342; 51 L. R. A. 414; 84 N. W. 3.

20 State v. Smith, 58 Minn. 35; 25 L. R. A. 759; 59 N. W. 545.

21 Kresser v. Lyman, 74 Fed. 765.

22 Eagle Ins. Co. v. Ohio, 153 U. S. 44G; Sandel v. Ins. Co., 53 S. C. 241; 31 S. E. 230.

23 Word v. Ins. Co., 112 Ga. 585; 37 S. E. 897. (The charter of the corporation forbade it to insure property for more than three-fourths of its value.) See Sec. 355.

24 St. Louis, etc., Ry. v. Mathews, 165 U. S. 1; (affirming Matthews v. Ry., 121 Mo. 298; 25 L. R. A. 161; 24 S. W. 591) ; Lake Erie, etc., Ry. v. Falk, 61 O. S. 312; 56 N. E. 203.

25 Central of Georgia Ry. v. Mur-phey, 116 Ga. 863; 60 L. R. A. 817; 43 S. E. 265.

26 Leavitt v. Ry., 90 Me. 153; 38 L. R. A. 152; 37 Atl. 886.

Statutes which require previously incorporated corporations of certain kinds, such as railroads,27 or corporations engaged in laying underground electric conductors,28 to contribute to the salary of commissioners having general supervision over such corporations, do not impair the obligation of any contract contained in the charters of such corporations. So a statute requiring payment of wages to certain classes of laborers within fifteen days of pay day, and making blacklisting a misdemeanor does not impair the obligation of such contracts of employment.29