Green’s Dictionary of Slang

1. a lawyer who specializes in representing the victims of street and other accidents, to whom he offers his services – often appearing at the victim’s hospital bed to promise a substantial claim – which are accepted while the victim is still too shocked to make proper and rational arrangements; thus chase ambulances v.

1886		Transactions of S. Carolina Bar Assoc. 87: Yet the ‘ambulance chaser’ has become a recognized feature of city life. He haunts the hospitals and visits the homes of the afflicted, officiously intruding his presence and persistently offering his services.
1897		Congressional Record 24 July 2961/1: In New York City there is a style of lawyers known to the profession as ‘ambulance chasers’, because they are on hand wherever there is a railway wreck, or a street-car collision or a gasoline explosion with [...] their offers of professional services.
1909		Springfield (MA) Weekly Republican 28 Jan. 6: The so-called ‘ambulance chasers,’ or lawyers who make a business of promoting damage suits against railroads and street railways on the basis of contingent fees.
1912		R.W. Brown ‘Word-List From Western Indiana’ in DN III:viii 570: ambulance lawyer, n. A lawyer who is always ready to help an injured person bring suit for damages. ‘He never has any big cases; he’s just an ambulance lawyer.’.
1913		S.F. Call 6 Mar.4/4: Victim of Streetcar Accident glancing at caller’s card — ‘I guess you’re an ambulance chaser, aren’t you?’ Lawyer (blandly) — ‘That’s rather a cruel name, old man’.
1915		Van Loan ‘The Spotted Sheep’ in Taking the Count 95: If one of those thieving ambulance chasers gets hold of this you may be sued on suspicion.
1927		(con. 1920s) S. Lewis Elmer Gantry 473: Mannie Silverhorn was one of the best ambulance-chasers in Zenith. A hundred times he had made the street-car company pay damages to people whom they had not damaged.
1928		Northern Whig (Antrim) 5 Oct. 8/4: In America, he alleged, there was frequently a scramble between the ‘ambulance chaser’ and the insurance company to reach the bedside of the injured.
1938		J.E. Hoover Persons in Hiding 123: Such persons as ambulance chasers, cappers for lawyers, bail bond fixers, and other forms of fungus which feeds on the misfortunes of crime.
1949		Monteleone Criminal Sl. (rev. edn).
1949		Yorks. Eve. Post 18 June 7/2: Good Lord! [...] Pelbury’s an ambulance chaser. He’s the most speculative lawyer in town.
1950		R.L. Bellem Blind Man's Fluff' in Thrilling Detective: Feb. 🌐 It's a new twist when an ambulance chaser gets on the scene ahead of the ambulance.
1960		(con. 1950-1960) R.A. Freeman Dict. Inmate Sl. (Walla Walla, WA) 2: Ambulance-chaser – a mouthpiece who plants the idea of suit, having in mind a juicy fee for his services.
1961		Guardian 14 Mar. 2/4: A new kind of ‘ambulance chaser’ – who were unscrupulous lawyers who collected details of casualties as they were taken to hospital in order to persuade the person concerned to bring action for damages.
1970		in P.R. Runkel Law Unto Themselves 238: Or, if I chose to be a lawyer, I wouldn’t need to be a mere ambulance chaser, shyster, or birdseed wiseguy.
1983		R. Price Breaks 11: Instead of goin’ to some ambulance-chaser factory on short notice, he’s gonna move back in with us.
1989		A. Sorkin A Few Good Men (1990) 63: Daniel, you’re an ambulance chaser with a rank. You’re nothing.
2005		J. Clancey Law and Its Sorrows 236: The term, ambulance chaser, implies going out after business, soliciting clientage [etc.].
2016		Twitter 20 Dec. 🌐 Gruesomely opportunistic ambulance chaser handed arse by man who knows what he’s talking about.

2. as ext. of sense 1, anyone, e.g. a journalist, pursuing sensational events.

1983

T. White Catch a Fire 261: The ambulance chasers of the Fourth Estate had moved on [from reggae] to exploit the rumours about snuff movies [...] and punk rock.