CIC 1867 The catechetical tradition also recalls that there are “sins that cry to heaven”: the blood of Abel,1 the sin of the Sodomites,2 the cry of the people oppressed in Egypt,3 the cry of the foreigner, the widow, and the orphan,4 injustice to the wage earner.5

CIC 2409 Even if it does not contradict the provisions of civil law, any form of unjustly taking and keeping the property of others is against the seventh commandment: thus, deliberate retention of goods lent or of objects lost; business fraud; paying unjust wages; forcing up prices by taking advantage of the ignorance or hardship of another.6
The following are also morally illicit: speculation in which one contrives to manipulate the price of goods artificially in order to gain an advantage to the detriment of others; corruption in which one influences the judgment of those who must make decisions according to law; appropriation and use for private purposes of the common goods of an enterprise; work poorly done; tax evasion; forgery of checks and invoices; excessive expenses and waste. Willfully damaging private or public property is contrary to the moral law and requires reparation.

CIC 2435 Recourse to a strike is morally legitimate when it cannot be avoided, or at least when it is necessary to obtain a proportionate benefit. It becomes morally unacceptable when accompanied by violence, or when objectives are included that are not directly linked to working conditions or are contrary to the common good.

CIC 2445 Love for the poor is incompatible with immoderate love of riches or their selfish use:
Come now, you rich, weep and howl for the miseries that are coming upon you. Your riches have rotted and your garments are moth-eaten. Your gold and silver have rusted, and their rust will be evidence against you and will eat your flesh like fire. You have laid up treasure for the last days. Behold, the wages of the laborers who mowed your fields, which you kept back by fraud, cry out; and the cries of the harvesters have reached the ears of the Lord of hosts. You have lived on the earth in luxury and in pleasure; you have fattened your hearts in a day of slaughter. You have condemned, you have killed the righteous man; he does not resist you.7

1 Cf. Gen 4:10.
2 Cf. Gen 18:20; 19:13.
3 Cf. Ex 3:7-10.
4 Cf. Ex 20:20-22.
5 Cf. Deut 24:14-15; Jas 5:4.
6 Cf. Deut 25:13-16; 24:14-15; Jas 5:4; Am 8:4-6.
7 Jas 5:1-6.